WO2023144555A1

WO2023144555A1 - Package and sleeve therefor

Info

Publication number: WO2023144555A1
Application number: PCT/GB2023/050191
Authority: WO
Inventors: Dane WHITEHURST
Original assignee: Duallok Limited
Priority date: 2022-01-28
Filing date: 2023-01-27
Publication date: 2023-08-03

Abstract

A package comprises first and second walls, joined by first and second side walls, and defining an internal volume therebetween. A retainer wall is locatable in the internal volume to lie against the first wall. A first locking feature is arrangeable inside the internal volume between the first wall and the retainer wall. A closure flap is coupled to the second wall at a forward end of the package. The closure flap is movable between a closed configuration in which the closure flap blocks access to the internal storage volume, and an open configuration in which the closure flap permits access to the internal storage volume via the forward end. The closure flap comprises a second locking feature configured such that when the closure flap is in the closed configuration the second locking feature is positioned inside the internal volume between the first wall and the retainer wall, such that the retainer wall forces the second locking feature into engagement with the first locking feature to lock the closure flap in the closed configuration. The first wall is flexible, to allow deflection of the first wall away from the retainer wall to cause movement of the first locking feature in an unlocking direction, thereby disengaging the first locking feature from the second locking feature to permit movement of the closure flap.

Description

PACKAGE AND SLEEVE THEREFOR This invention relates to a latchable package such as a box, which may be used in the packaging of items. In particular, though not exclusively, the invention relates to a child- resistant package for storing potentially hazardous materials which must be kept safe from children or irresponsible adults. The safe storage of potentially hazardous materials has long been a problem for families with young children. Whilst parents need or desire access to a wide range of hazardous materials, the natural curiosity of children can cause them to seek out and ingest such materials when unsupervised. This can have serious consequences. For example, an overdose of virtually any pharmaceutical is injurious to health. Indeed some pharmaceuticals are entirely unsuitable for children and have an adverse effect on the health of children even if handled or ingested in very small quantities. For the sake of simplicity, potentially hazardous materials such as those described above will hereinafter simply be referred to as “hazardous materials”. Additionally, the problems described above are not limited to children and can also arise in respect of irresponsible or forgetful adults, such as for example some mentally ill or mentally disabled patients, or the elderly who may be prone to confusion as to the contents of a package. Whilst the focus of this specification is on children, it will be appreciated that the majority of what is described herein applies analogously to irresponsible or forgetful adults. All such analogies are within the scope of this specification, even where reference is made only to children. In light of their dangerous nature, hazardous materials must be kept out of the reach of children. This is an established practice that is of fundamental importance and which may be augmented, but can never be replaced, by child resistant closures (CRCs). CRCs make it harder for children to extract hazardous materials from a package, if they do manage gain access to them in packaged form. Many CRC designs have been suggested in the past. However, such CRC designs are often complicated in structure and expensive to manufacture. In particular, assembly processes are typically longer and more complex for child-resistant packages, which results in a costlier manufacturing process. Since the cost of packaging is generally passed on to consumers, this leads consumers to buy products in non-resistant packaging where available, thereby increasing the risk of accidental poisonings and the like. Minimising complexity of a CRC design and its manufacturing process, and hence minimising its cost, is therefore crucial in providing a successful CRC. It is important to balance the child-resistance of a CRC with reasonable ease of opening for adults wishing to access the contents of the package. For example, adults needing to take medication housed in the package may be physically impaired. A further design consideration is that once a CRC has been opened, it is important that it can be easily and perceptibly returned to a secured position. If the mechanism for returning the CRC to a secured position is too complicated, the user may omit to return the CRC to the secured position, thereby leaving the hazardous material more easily accessible. If it is not obvious to the user that the CRC has been returned to the secured position, the user may inadvertently fail to secure the package correctly before it is returned to its storage place, negating the child-resistant design. Many CRCs incorporate plastics components. In particular, in CRC designs that incorporate a locking feature for child resistance, the locking feature is often formed of plastic material, so as to provide the high degree of durability that is desirable for a CRC. However, such plastics components are not environmentally-friendly, and it would be desirable to provide a plastics-free option that provides the required level of rigidity and child resistance. It is an object of this invention to address at least one of the problems described above. Statements of the invention Against this background, the invention resides in a package comprising first and second walls, joined by first and second side walls, and defining an internal volume therebetween; a retainer wall locatable in the internal volume to lie against the first wall; a first locking feature arrangeable inside the internal volume between the first wall and the retainer wall; and a closure flap coupled to the second wall at a forward or first end of the package. The closure flap is movable between a closed configuration in which the closure flap blocks access to the internal storage volume, and an open configuration in which the closure flap permits access to the internal storage volume via the forward end. The closure flap comprises a second locking feature configured such that when the closure flap is in the closed configuration the second locking feature is positioned inside the internal volume between the first wall and the retainer wall, such that the retainer wall forces the second locking feature into engagement with the first locking feature to lock the closure flap in the closed configuration. The first wall is flexible, to allow outward deflection of the first wall to cause movement of the first locking feature in an unlocking direction, thereby disengaging the first locking feature from the second locking feature to permit movement of the closure flap. In this way, when the package is in the closed configuration, the first and second latch members are held between the retainer wall and the first wall, which urge the latches into engagement. To unlatch the package, the user causes deflection of the flexible first wall away from the retainer wall, which provides room for the latch features to disengage. The user can then open the package. The package is easily operated by an adult, but difficult to operate for a child, thereby providing effective child resistance. The first locking feature may comprise a locking flap that protrudes into the internal volume between the first wall and the retainer wall. The first locking feature may be coupled to the first wall. In this case, when the closure flap is in the closed configuration, the second locking feature may be located between the retainer wall and the first engagement feature, and the first engagement feature may be located between the second engagement feature and the first wall. The locking flap may be coupled to the first wall via a fold or crease. The fold or crease acts to bias the locking flap away from the first wall and towards the second locking feature. The fold or crease may be provided at a forward end of the first wall. The locking flap may be continuous with the first wall. The locking flap may comprise a locking protrusion. The second locking feature may comprise an opening formed in the closure flap, which may be an aperture. The locking protrusion may be configured to protrude into in the opening when the closure flap is in the closed configuration, to prevent movement of the closure flap from the closed configuration to the open configuration. The closure flap and locking flap may be configured such that, when the closure flap is in the closed configuration, a lower edge of the closure flap is located below a lower edge of the opening. In other words, when the closure flap is in the closed configuration, the locking flap may extend fully through the opening in the closure flap, such that the lower edge of the opening of the closure flap is closer than the lower edge of the locking flap to the first or front wall of the sleeve, for improved engagement between locking features of the package. In other embodiments, the closure flap and locking flap may be configured such that, when the closure flap is in the closed configuration, a lower edge of the closure flap is substantially aligned with a lower edge of the opening. The closure flap may comprise a top cover that covers an open end of internal volume, and an extension flap that extends into internal volume between the first wall and the retainer wall when the closure flap is in the closed configuration. The extension flap may include a tapered portion such that a width of the extension flap adjacent the tapered portion is smaller than a width of the first or front wall. In this way, small gaps are provided between side edges of the extension flap and side edges of the front wall to allow space for a user to squeeze side walls of the sleeve together to deflect the front wall and unlatch locking features of the package. Alternatively, a width of the extension flap may be substantially the same as a width of the front wall of the package so as to guard against deflection of the front wall when a user squeezes side walls, and in particular side edges of the front wall, of the package. The closure flap may comprise a crease or fold that defines a boundary between the top cover and the extension flap. The crease or fold may define a curve across the width of the closure flap, so as to provide a curved boundary between the top cover and the extension flap. In such embodiments, the curved crease or fold defines a curved first or front edge of the top cover. The curved front edge improves engagement between the top cover and the front wall of the package in the closed configuration. The extension flap may comprise a fold, and the opening may straddle the fold. A spacing between the first and second side walls defines a width of the internal volume of the package. A width of the retainer wall at the forward end of the package may be less than the width of the internal volume. Having a reduced width at the forward end allows space for the side walls to be squeezed slightly towards each other to cause deflection of the first wall, while avoiding any deflection of the retainer wall. In this way the first wall is deflected while the retainer wall is not, which permits unlatching of the latch formations. The retainer wall may comprise a protrusion region having one or more side protrusions, and wherein a width of the retainer wall in the protrusion region is greater than the width of the retainer wall at a forward end of the package. The protrusion region may comprise first and second protrusions on opposite sides of the retainer wall. The protrusion region may encompass a central region of the retainer wall. Alternatively or additionally, the protrusion region may encompass a rearward region of the retainer wall. The package may further comprise a brace coupled to the retainer wall and configured to brace against the second wall, so as to restrict movement of the retainer wall away from the first wall. The brace may comprise a pair of brace walls that project away from the retainer wall towards the second wall. The package may further comprise a guard flap coupled to a forward end of the retainer wall, and selectively arrangeable to cover a forward end of the internal volume. The guard flap may be coupled to the retainer wall by a crease or fold. The crease or fold may define a curved boundary between the guard flap and the retainer wall. The guard flap may comprise an access opening. The first wall may comprise an inner first wall and an outer first wall that overlies and is coupled to the inner first wall. The inner first wall and outer first wall may be coupled with an adhesive. The package may comprise first and second reinforcement walls that extend between the closure flap and the respective side walls. Each reinforcement wall may be coupled to each of the closure flap and respective side wall by a coupling crease. Each reinforcement wall may comprise a further crease between the coupling creases, to allow the reinforcement wall to fold when the closure flap is moved from the open configuration to the closed configuration. The reinforcement wall may therefore define a concertina fold. The reinforcement wall may provide a spring force between the closure flap and respective side wall by means of the fold. The package may comprise an outer sleeve that defines the internal volume, and an insert that is insertable into the internal volume, wherein the retainer wall is defined by the insert. The brace may also be defined by the insert. The outer sleeve may be formed as a separate piece from the insert. Alternatively, the outer sleeve and the insert may be formed from the same piece. In this case, the insert may be coupled to the second wall at a rearward end, such that the insert extends from a rearward end of the second wall through the internal volume towards a forward end of the package. The package insert may be coupled to the second wall via a closure flap. The package may comprise a third locking feature coupled to one of the first wall or the second wall at a rearward end of the package, the third locking feature being arrangeable inside the internal volume between the first wall and the retainer wall, or between the second wall and a further retainer wall; and a further closure flap coupled to the other of the first wall or the second wall at a rearward end of the package. The further closure flap may be movable between a closed configuration in which the further closure flap blocks access to the internal storage volume, and an open configuration in which the further closure flap permits access to the internal storage volume via the rearward end. The further closure flap may comprise a fourth locking feature configured such that when the further closure flap is in the closed configuration the fourth locking feature is positioned inside the internal storage volume between the third locking feature and the retainer wall, or the further retainer wall such that the retainer wall or the further retainer wall forces the fourth locking feature into engagement with the third locking feature to lock the closure flap in the closed configuration. At least a part of the package may be made of a cardboard or paperboard material. The sleeve may be made from a cardboard or paperboard material. Optionally the entire package may be made from a cardboard or paperboard material. The package may further comprise an engagement feature configured to be engaged by the user to facilitate deflection of the first wall. The engagement feature may comprise a grip on the first wall. The grip may be a pull feature such as a tab or ribbon, or the grip may be an opening or aperture. The locking flap may comprises a weakening feature configured to facilitate deflection of the first locking feature away from the retainer wall. The weakening feature may be configured to bias a central region of the locking flap away from the retainer wall. The weakening feature may comprise one or more folds, creases, scores, perforations or openings on the locking flap. The weakening feature may be provided in a central region of the locking flap. Where the weakening feature is a fold, crease, score or perforation, the fold, crease, score or perforation may extend along a length of the locking flap. The weakening feature may define a tapered profile on the locking flap. The package may include press markings spanning side edges of the front wall to identify a preferable press location for opening of the package. The press markings may comprise printed graphics, holes, slots, perforations, creases which may be discontinuous, or other appropriate indicators. The invention also extends to a sleeve for use with an insert to provide a latchable package, the insert having a retainer wall and the sleeve comprising first and second walls, joined by first and second side walls, and defining an internal volume therebetween, the internal volume capable of receiving the insert such that the retainer wall of the insert lies adjacent to the first wall; a first locking feature arrangeable inside the internal volume between the first wall and the retainer wall of the insert; and a closure flap coupled to the second wall at a forward end of the sleeve. The closure flap is movable between a closed configuration in which the closure flap blocks access to the internal volume, and an open configuration in which the closure flap permits access to the internal volume via the forward end. The closure flap comprises a second locking feature configured such that when the closure flap is in the closed configuration the second locking feature is positioned inside the internal volume between the first wall and the retainer wall of the insert, such that the retainer wall forces the second locking feature into engagement with the first locking feature to lock the closure flap in the closed configuration. The first wall is flexible, to allow deflection of the first wall away from the retainer wall of the insert to cause movement of the first locking feature in an unlocking direction, thereby disengaging the first locking feature from the second locking feature to permit movement of the closure flap. Such a sleeve can be retrofitted over an insert (i.e. by inserting the insert into the internal volume), so that a child resistant package is created. The insert may for example constitute a package, so that the sleeve can be used to confer child resistance on an existing package. Optional and preferred features of one aspect of the invention may be used alone, and in appropriate combination, with other aspects of the invention also. Brief description of the figures In order that the invention may be more readily understood, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a perspective view of a latchable package according to an embodiment of the invention in a first or closed configuration; Figure 2 is a perspective view of the latchable package of Figure 1 in a second or open configuration; Figure 3 is a perspective view of a sleeve forming part of the package of Figure 1 when assembled for use, with internal features indicated in dashed lines; Figure 4 is a partial enlarged view of a locking flap forming part of the sleeve of Figure 3; Figure 5 is a plan view of a blank that can be assembled into the sleeve of Figure 4; Figure 6 is a perspective view of an insert forming part of the package of Figure 1 when assembled for use, with internal features indicated in dashed lines; Figure 7 is a plan view of a blank that can be assembled into the insert of Figure 6; Figures 8 to 10 are front cross sectional views of the assembled package taken at the forward end, with Figure 8 showing the package in the open configuration, Figure 9 showing the package in a closed and latched configuration, and Figure 10 showing the package in a closed and unlatched configuration; Figure 11 is a perspective view of a front end of the package of Figure 1 in the closed configuration, with internal features indicated in dashed lines; Figures 12 and 13 are side cross sectional views of the package, with Figure 12 showing the package in a closed and latched configuration, and Figure 13 showing the package in a closed and unlatched configuration; Figure 14 is a side view of the package in a partially-open configuration; Figure 15 is a perspective view of a sleeve forming part of a package according to another embodiment of the invention; Figure 16 is a perspective view of an insert forming part of a package according to another embodiment of the invention; Figure 17 is a side cross sectional views of the package comprising the sleeve of Figure 14 and the insert of Figure 15, with the package in the closed and latched configuration; Figure 18 is a perspective view of a package according to a further embodiment of the invention, in the open configuration, with internal features indicated in dashed lines; Figure 19 is a plan view of a blank that can be assembled into the package of Figure 18; Figures 20 to 22 are partial enlarged views from above showing variations of a locking flap according to further embodiments; Figure 23 is a plan view of a blank that can be assembled into a sleeve of another embodiment; Figure 24 is a plan view of a blank of an insert of another embodiment; and Figures 25 and 26 are perspective views of a package in a closed configuration, comprising a sleeve in accordance with the embodiment of Figure 23 and an insert in accordance with the embodiment of Figure 24. Detailed description of embodiments of the invention Referring to Figures 1 and 2, a child resistant package 100 comprises a sleeve 200 that surrounds an internal volume 50 that can store hazardous materials. The sleeve 200 comprises a first wall in the form of a front wall 202, and a second wall in the form of a rear wall 204. The front and rear walls 202, 204 are joined by a left side wall 206, a right side wall 208. The front, rear and side walls surround the internal volume 50. The package also comprises a retainer wall 310 (not visible in Figures 1 and 2), which is provided as part of an insert 300 that is received in the internal volume 50, such that the retainer wall 310 lies against the front wall 202. At a forward end 112 of the package 100, the sleeve 200 comprises a lid or closure flap 250 that is moveable between a closed configuration, shown in Figure 1, and an open configuration, shown in Figure 2. In the closed configuration, the closure flap 250 blocks access to the internal storage volume 50. In the open configuration, the closure flap 250 is arranged to permit access to the internal volume 50 via the forward end 112. As will be described in more detail below, and as is visible in Figures 3 and 5, a first locking feature 400 is provided on the package 100 and arranged to lie between the retainer wall 310 and the front wall 202. In this case, the first locking feature 400 is provided on the front wall 202 of the sleeve 200. A second locking feature 500 is provided on the closure flap 250. The second locking feature 500 is arranged such that when the closure flap 250 is in the closed configuration, the second locking feature 500 lies between the front wall 202 and the retainer wall 310, and lies adjacent to the first locking feature 500. The retainer wall 310 pushes the second locking feature 500 into engagement with the first locking feature 400, i.e. so that the locking features 400, 500 are in an engaged configuration. When the closure flap 350 is in the closed configuration, and the locking features 400, 500 are in an engaged configuration, the locking features 400, 500 prevent the closure flap 350 being moved into the open configuration. The package is therefore locked to prevent access. As will be described in more detail, the locking features 400, 500 can be disengaged by causing outward deflection of the front wall 202 at the forward end 112 of the package 100 in the direction D – i.e. a direction away from the retainer wall 310 - (see Figure 1), for example by applying inward pressure to the side walls 206, 208 in the direction P (see Figure 1). When the latches 400, 500 are disengaged, the closure flap 250 can be moved into the open configuration to access the contents stored in the internal volume 50. Figures 3, 4 and 5 shows the sleeve 200 in isolation, with ‘internal’ features of the sleeve 200 in dashed lines. Figure 3 illustrates the sleeve 200 assembled for use, Figure 4 shows a close up of a locking flap 402 forming part of the sleeve, and Figure 4 illustrates the flat blank 200a that can be folded to form the sleeve 200. Referring to Figure 3, a spacing between internal faces of the left and right side walls 206, 208 defines a width Vw of the internal volume 50. At a forward end 112 of the front wall 202 of the sleeve 200, the front wall 202 is coupled to a locking flap 402. The front wall 202 and locking flap 402 are continuous with each other, with a fold or crease 404 defining the boundary therebetween. When the package 100 is assembled for use, the locking flap 402 is folded back against the front wall 202, i.e. with the locking flap 402 lying parallel to and against the front wall 202. The fold acts to bias the locking flap in a locking direction that is away from the first wall. As best seen in Figure 4, the locking flap 402 comprises an extension portion 406 that is adjacent to the front wall 202, and a locking protrusion 408 that protrudes from the extension portion 406 to define the first locking feature 400. The extension portion 406 is tapered in width, so that its width decreases moving away from the fold 404 towards the locking protrusion 408. The locking protrusion 408 therefore has a smaller width than the front wall 202. The locking protrusion 408 comprises straight side edges 410 that lead towards a locking end of the locking protrusion 408. At the locking end, the locking protrusion 408 terminates in a locking edge 412. The locking edge 412 is shaped as a blunt, gently tapered point, with slightly tapered side regions, and a blunt horizontal end. Referring back to Figure 3, at a forward end 112 of the rear wall 204 of the sleeve 200, the rear wall 204 is coupled to the closure flap 250. The rear wall 204 and closure flap 250 are continuous with each other, with a fold or crease 220 defining the boundary therebetween. The closure flap 250 comprises a top cover 252 that is adjacent to the rear wall 204, and an extension flap 254 that extends away from the top cover 252. When the closure flap 250 is in the closed configuration of Figure 1, the top cover 252 covers an open end of internal volume 50 to block access, while the extension flap 254 extends into internal volume 50 between the locking flap 402 and the retainer wall 310. A lower insertion edge 270 of the extension flap 254 has rounded corners, to facilitate insertion of the extension flap 254 into the internal volume 50. The extension flap 254 and the top cover 252 are continuous with each other, with a fold or crease 256 defining the boundary therebetween. The extension flap 254 also comprises a further fold or crease 258. In this case the further fold 258 is approximately halfway down the extension flap 254, though it may be at other locations. The second locking feature 500 is provided on the extension flap 254, and takes the form of a locking aperture 260. In this example, the locking aperture straddles the further crease 258. The locking aperture 260 has substantially the same shape as the locking protrusion 408 of the locking flap 402. The locking aperture 260 is therefore surrounded by a generally horizontal top edge 262, short side edges 264, and a locking edge 266. The locking edge 266 defines the same shape as the locking edge 412 on the locking protrusion 408, with tapered with slightly tapered side regions, and a blunt horizontal end. The top cover 252 is joined to the side walls 206, 208 by reinforcement walls 280. Each reinforcement wall 280 is coupled to each of the top cover and the respective side wall 206, 206 by a coupling crease 282. Each reinforcement wall also comprises a further crease 284 at a mid-point between the two coupling creases 282. The coupling creases 282 and the further crease 284 are arranged to allow the reinforcement wall 280 to fold and collapse as the closure flap 250 is moved into the closed configuration, so that the reinforcement walls 280 do not impeded opening and closing of the closure flap. In this example, the further crease 284 is at a 45º angle to the coupling creases 282, though other arrangements are possible. The reinforcement wall 280 also comprises an aperture 286 adjacent to the corner where the top cover 252 meets the side wall 206, 208. This aperture 286 facilitates the folding and collapse of the reinforcement wall 280. The concertina-like folding means that the reinforcement walls provide a slight spring force that generally urges the closure flap 250 open. In this embodiment, at a rear end 114 of the sleeve 200, the package is provided with a further locking flap 402a, and a further closure flap 250a. The further locking flap 402a and further closure flap 250a are a mirror image of the locking flap 402 and closure flap 250 already described, and hence are substantially identical, with the same features and function. In other embodiments, the further locking flap 402a and further closure flap 250a may be omitted, and may be replaced with a simple closed rear end of the package, or they may be replaced with other features as described in later embodiments. As can be seen in Figure 5, the sleeve 200 is formed from a blank 200a that comprises a single continuous sheet. The sheet may be made of and suitable material such as a cardboard, paper board or plastics material. In a particularly preferred embodiment the sleeve is made of cardboard. To secure the folded blank, one of the walls of the sleeve is configured as a double wall, comprising inner and outer walls that are secured together, for example by an adhesive. In this example, the front wall 202 comprises an inner front wall 202a and an outer front wall 202b. The inner front wall 202b underlies the outer front wall 202a, with the walls overlapping completely and secured together. In other examples, a different wall may comprise inner and outer walls and act to secure the package. The inner and outer walls may not completely overlap: for example, the inner wall may be provided as a tab of reduced width compared to the outer wall. Figures 6 and 7 illustrate the insert 300, which in this embodiment is formed as a separate piece from the sleeve 200. Figure 6 illustrates the insert 300 assembled for use, and Figure 7 illustrates a flat blank 300a that can be folded to assemble the insert 300. The insert 300 comprises a retainer wall 310. Towards a forward end 112, the retainer wall 310 defines a retainer locking feature 312 in the form of a retainer locking aperture. The retainer locking aperture 312 is substantially the same shape as the locking aperture 260 in the closure flap 250, and is positioned so that so the locking aperture 260 in the closure flap 250 aligns with the retainer locking aperture 312 when the closure flap 250 is in the closed configuration. In this embodiment, the retainer wall also defines a further locking aperture 312a towards a rearward end 114 of the insert. At left and right sides of the insert 300, the insert comprises brace walls 304 that are continuous with the retainer wall 302, and join the retainer wall 302 at a crease or fold 306. The brace walls 304 are substantially the same size and shape as the side walls 206, 208 of the sleeve 200, and in particular have the same depth. In use, when the insert 300 is inserted into the sleeve 200, the brace walls 304 project away from the retainer wall 310 to define a brace that braces against the rear wall 204 of the sleeve 200. This bracing effect restricts movement of the retainer wall 310 away from the front wall 202. At left and right sides of the retainer wall 310, a central or projection region 315 of the retainer wall 310 comprises an elongate projection 314 that protrudes a short distance beyond the fold 306. Each elongate projection 314 comprises an outer edge 316. As best seen in Figure 7, each brace wall 304 comprises a corresponding cut out 308 that accommodates the protrusion 314. The protrusions act to alter the width of the retainer wall 310 in the protrusion region 315. In particular, as best seen in Figure 7, at a forward end 112 of the retainer wall 310, a first width Rw is defined between outer sides of the retainer wall, while in the protrusion region 315, a second width Rw’ is defined between outer edges of the protrusions 314. The second width Rw’ is substantially the same as the width Vw of the internal volume (i.e. the internal spacing between the side walls 206, 208). The first width Rw is smaller than the second width Rw’, and hence is smaller than the width Vw of the internal volume. This means that, in the assembled package, at the forward end 112 of the package 100 there is a small clearance between the retainer wall 300 and the side walls 206, 208, while in the protrusion region 315, there is substantially no clearance, and the protrusions 314 of the retainer wall 310 brace against the side walls 206, 208. At a forward end 112 of the insert 300, the retainer wall 310 is coupled to a guard flap 330. The guard flap 330 and the retainer wall 310 are continuous with each other, and a crease or fold 332 defines a boundary therebetween. The guard flap comprises an access opening or cut-out 334 opposite the crease, which can accommodate the tip of a user’s finger to facilitate opening and closing of the guard flap. In this embodiment, the rear end 114 of the insert 300 is substantially the same as the forward end of the insert 300, i.e. with a further locking aperture 312a, and a further guard flap 330a. A width of the retainer wall 310 at the rear end is equal to the width Rw of the retainer wall at the forward end. However, embodiments are envisaged in which the rear end 114 differs from the forward end 112. In the assembled package 100, the insert 300 is inserted into the sleeve so as to sit in the internal volume 50 of the package 100. Figure 8 is a schematic cross section taken at the front end 112 of the package with the closure flap in the open configuration, and illustrates schematically the relative location of the insert 300. As can be seen in Figure 8, the retainer wall 310 of the insert 300 lies against the locking flap and front wall 202. To close the package, a user inserts the lower insertion edge 270 of the extension flap 254 between the retainer wall 310 and the locking flap 402, and pushes the closure flap 250 downwards until the top cover 252 covers the open end of the internal volume 50. Figure 9 shows a schematic cross section taken at the front end 112 of the package with the closure flap in the closed configuration, showing the extension flap 254 located between the retainer wall 310 and the locking flap 402. As best seen in Figures 11 and 12, when the closure flap 250 is in the closed configuration, the locking aperture 260 in the closure flap 250 aligns with the locking protrusion 408 on the locking flap 402, and with the aperture 312 in the retainer wall 310. The fold 404 at the top of the locking protrusion 408 means that the locking protrusion 408 is naturally biased away from the front wall 202 and towards the extension flap 254 and the retainer wall 310. The retainer wall 310 is pushed towards the front wall 202 by the brace walls 304. The opposed biasing of the locking flap 402 and the retainer wall 310 acts to bias the locking protrusion 408 so that it protrudes into the locking aperture 260 of the closure flap 250 and the aperture 312 of the retainer wall 310, as is best seen in Figure 12. If a user attempts to move the closure flap 250 in an opening direction O with the package in the configuration of Figure 11 and 12, the attempted movement will cause the lower edge 266 of the locking aperture 260 to move into contact with the lower edge 412 of the locking protrusion 408. Movement of the closure flap 250 will therefore be halted. If the user tries to force the movement, the locking protrusion 408 will protrude deeper into the locking aperture 260, causing an even more secure lock. If the locking flap becomes deformed or pulled off centre, for example due to continuous use or rough handling, the tapered point of the locking edge 412 and tapered side regions provide a substantial abutment edge that will still abut against the locking aperture even if the horizontal tip does not make contact. The tapered shape therefore assists in ensuring a good locking function even if the locking protrusion is slightly deformed. To open the package 100, the user must disengage the locking formations 400, 500. To do this, the user must cause deflection of the front wall 202 in a disengagement direction D, which is out of the plane of the front wall 202, away from the retainer wall 310. This deflection is shown in Figures 10 and 13. In this embodiment, the user causes the deflection by squeezing the side walls 206, 208 together, applying inward pressure in a direction P, shown in Figure 10. This squeezing motion acts to close the small clearance between the side walls 206, 208 and the retainer wall 310, reducing the separation between the side walls 206, 208 at the forward end 112 of the package. The protrusions 314 (see Figures 6 and 7) provide structural rigidity at the central region of the package, so that the side walls cannot be pushed inwards at the centre of the package. The limits the inward movement only to the region where pressure is applied by the user. Because the front wall 202 is flexible, the reduction in separation is accommodated by deformation of the outer wall 202. Because the retainer wall is unaffected by the inward pressure, and is braced against the outer wall the outer wall 202, the outer wall 202 cannot deflect towards the retainer wall 310. Instead, the outer wall 202 must deflect outwards, in direction D away from the retainer wall 310. Since the locking flap 402 is coupled to the outer wall 202, this outward deflection of the outer wall 202 causes a corresponding deflection of the locking flap 204. As best seen in Figure 13, this draws the locking protrusion 408 out of the locking aperture 260, thereby causing disengagement of the locking protrusion 260 and the locking aperture (i.e. disengagement of the first locking feature 400 and the second locking feature 500). In this disengaged configuration of Figures 10 and 13, the locking features 400, 500 no longer prevent movement of the closure flap 250, and the closure flap can be moved in the opening direction O without hindrance, as shown in Figure 14. As best seen in Figure 2, when the closure flap 250 is fully open, the internal volume 50 is closed only by the guard flap 330. The guard flap can be easily moved by the user, by inserting a finger into the access opening 334, and hinging the guard flap 330 about the hinge 332, to access the internal volume 50. It will be appreciated that at the rear end 114 of the package, the further closure flap 250a and further locking flap 402a operate in exactly the same way. In this embodiment, the package 100 can therefore be opened from either end 112, 114. The tightness of the lock may be tuned to some extend by varying the exact position of the locking protrusion 408 and the locking aperture 260. In particular, the relative positions of the locking edge 412 of the locking protrusion 408 and the locking edge 266 of the aperture 260 can be altered to effect the tightness of the lock. In the embodiment described here, the locking edge 412 of the locking protrusion 408 and the locking edge 266 of the aperture 260 are substantially aligned with one another. In other embodiments, the locking edge 412 of the locking protrusion 408 may be slightly lower than the locking edge 266 of the aperture 260 when the closure flap 250 is closed, so as to ensure a particularly secure lock. In this case, to unlock the package 100 in addition to squeezing the sidewalls 206, 208, the user may need to push to closure flap 250 slightly downwards, i.e. opposite to the opening direction O, to move the locking edge 266 of the aperture 260 slightly below locking edge 412 of the locking protrusion 408. The need to perform these movements simultaneously increases the child resistance of the lock. If desired, the tightness of the lock may be different at the forward end 112 and the rearward end 114 of the package 100. For example, the lock may be tighter at the rear end 114 of the package, so that it is harder to open the package at the rear end. In some embodiments it may be desirable to make the lock so tight at the rear end 114 that it is impossible or near-impossible to open the lock manually. Figures 15 and 16 illustrate a sleeve 1200 and an insert 1300 respectively forming part of a package according to another embodiment of the invention. The package is substantially the same as the package of Figures 1 to 14, except for the differences that are described below. Firstly, a rear end 1114 of the package comprises a simple unlatched closure, in place of the further closure flap and locking flap. The simple closure at the rear end 1114 may be secured in place by an adhesive or other suitable means, so that the internal volume 1050 cannot be accessed via the rear end 1114. Secondly, the insert 1300 comprises an additional wall 1340 opposite the retainer wall 1310. In this example, the additional wall 1340 is coupled to the guard flap 1330a at the rear end of the insert 1300. In particular, the additional wall 1340 and guard flap 1330a are continuous with each other and joined by a fold or crease 1342. At a forward end 1112, the additional wall 1340 comprises an access opening 1344, which facilitates the user’s access to the access opening 1334 in the guard flap 1330 at the forward end 1112. Thirdly, the retainer wall 1310 of the insert 1300 does not comprise an aperture. This means that, as shown in Figure 17, when the closure flap 1250 is in the closed configuration, the locking protrusion 1408 protrudes only into the locking aperture 1260 on the closure flap 1250, and contacts the retainer wall 1310 through that aperture. The latching and unlatching of the package is otherwise identical. At the front end 1112, the sleeve 1200 and insert 1300 are have all the features of the sleeve 200 and insert 300 of the embodiment of Figure 1 to 14. In particular, the latch formations and retainer wall interact in the same way, and the user unlatches and opens the package in the same way. Figures 18 and 19 illustrate another embodiment of a package 2100. In this embodiment, the sleeve 2200 and the insert 2300 are provided as part of the same piece, such that they are integral with each other. Figure 18 illustrates the package 2100 in an open configuration, and Figure 19 illustrates a flat blank 2100a that can be folded to produce the package 2100. Considering first the part of the package that defines the sleeve 2200, the forward end 2112 of the sleeve 2212 is substantially identical to the forward end of the sleeve in the embodiment of Figures 1 to 14. The rear end 2114 of the sleeve 2200 differs in ways that will now be described. As best seen in Figure 19, at the rear end 2214 of the sleeve 2200, the sleeve is provided with a rear closure flap 2250a. In this embodiment, the rear closure flap 2250a is coupled to the insert 2300, so that the insert is insertable into the internal volume 2050 of the package 2100 via the rear end 2214 of the sleeve 2200. The rear closure flap 2250a comprises a cover 2252a that defines a substantially flat panel. The cover 2252a is coupled to side walls 2206, 2208 of the sleeve via reinforcement walls 2280 in the same manner as the top cover 252 described in relation to the embodiment of Figure 1 to 14. A lower end of the cover 2252a is coupled to a lower end of the insert 2300 by a fold. The insert 2300 therefore extends away from the lower end of the cover 2252a. As shown in Figure 19, in the flat blank 2100a, the insert 2300 extends downwardly away from the cover 2252a, but when the package 2100 is assembled for use, the insert 2300 is folded upwards into the internal volume 2050, so that the insert 2300 extends perpendicularly to the cover 2252a, lying beneath the front wall 2202. The insert 2230 comprises a plurality of sections, demarcated by creases or folds. The sections will now be described starting from the lower end as shown in Figure 19, which corresponds to the forward end 2112 of the package 2100 when the package is assembled as in Figure 18. At the forward end 2112, the insert 2300 comprises a guard flap 2330 that is substantially the same as the guard flap 230 of Figure 6. Subsequent panels comprise a forward panel 2332, a protrusion panel 2334, a first rear panel 2336, and a second rear panel 2338. Together these four panels 2332, 2338, 2336, 2338 define the retainer wall 2330 of the insert 2300. The guard flap 2330 is coupled to the forward panel 2332. Side edges of the forward panel 2332 are coupled to brace walls 2304, which perform the same function as the brace walls 304 of Figure 6. A width of the forward panel 2332 between the side edges (i.e. a width of the retainer wall 2310 at the forward end) is Rw, which is less than the width Vw of the internal volume 2050. The forward panel 2332 is coupled to the protrusion panel 2334. The protrusion panel has a width Rw’ that is wider than the width Rw, and substantially to same as the width Vw of the internal volume 2050. The protrusion panel 2334 there fore protrudes slightly further widthways than the forward panel 2332, thereby defining protrusions 2314 at the outer most edges. These protrusions 2314 have the same function as the protrusions 314 of Figure 6. The protrusion panel 2334 is coupled to the first rear panel 2336. The first rear panel 2336 has a width Rw, i.e. substantially the same as the width of the forward panel 2332. The first rear panel 2336 is coupled to the second rear panel 2338. The second rear panel 2238 is coupled to the cover 2252a, thereby coupling the insert 2300 to the sleeve 2200. The second rear panel 2238 may be provided with an adhesive layer on the underside as shown in Figure 19, so that when the insert 2300 has been arranged inside the internal volume 2050 against the front wall 2202 as shown in Figure 18, the second rear panel 2238 can be adhered to the interior surface of the front wall 2202. To assemble the package 2100, the user first assembles the sleeve portion 2200 by folding the sleeve 2200 until the outer front wall 2202b overlies the inner front wall 2202b. The outer front wall 2202b and the inner front wall 2202b are adhered together to form the front wall 202. This creates the internal volume 2050, which is open at its rear end 2114. The locking flap 2402 is folder over the front wall 2202, and the sleeve portion 2200 is complete. The user then inserts the insert portion 2300 into the internal volume 2050 by folding the insert portion 2300 upwards and feeding it into the internal volume 2050 from the rear end 2114 of the package 2100. First the user feeds in the guard flap 2230, then the forward panel 2232, and so on, until the entire insert 2300 is inside the interior volume 2050. As the user inserts the forward panel 2232, the retainer walls 2314 are folded to lie perpendicular to the forward panel 2232, so that the forward panel 2232 and retainer walls 2314 will fit into the opening at the rear end 2114. As the forward panel 2232 reaches the forward end 2212, the user ensures that the locking flap 2204 is arranged to sit between the front wall 2202 and forward panel 2232 (i.e. retainer wall 2310) of the insert 2300. The folds between the panels 2230, 2232, 2234, 2236, 2238 facilitate insertion of the insert 2300 into the opening by allowing the insert 2300 to be gradually rolled up into the internal volume 2050. Once the insert portion 2300 has been inserted into the internal volume 2050 the package is in the configuration shown in Figure 18, and the second rear panel 2238 can be adhered to the front wall 2202. The insert 2300 performs the same function as the insert of the embodiments of Figures 1 to 14 and 15 to 16. For example, the brace walls 2304 push the retainer wall 2310 against the locking flap 2402 in the same way, thereby causing engagement between the latch features in the same way. The difference between the width Rw of the retainer wall 2310 in the front region 2232, and the width Vw of the internal volume permits the squeeze action of the side walls and deflection of the front wall 202 in the manner shown in Figures 10 and 13, to allow disengagement of the latches. Opening and closing of the closure flap 2250 therefore occurs in the same way as already described in relation to the embodiment of Figures 1 to 14. Figures 20 to 22 illustrate locking flaps according to other embodiments of the invention, in which the locking flap is provided with a weakening feature that tune the tightness of the lock. In Figure 20, the locking flap 3402 comprises a weakening feature in the form of a crease or fold 3405 that extends along the length of the locking flap i.e. from the crease or fold 3402 that acts as the boundary between the front wall 3202 and the locking flap 3402, to the locking edge 3412 of the locking flap 3402. In Figure 21, the locking flap 4402 additionally comprises a small opening 4407 that acts as a further weakening feature. In Figure 22 the weakening feature comprises a perforation 5409, i.e. a series of scores, cuts or openings, that also extends along the length of the locking flap 5402 i.e. from the crease or fold 5404 that acts as the boundary between the front wall 5202 and the locking flap 5404, to the locking edge 5412 of the locking flap 5402. In all these examples, the weakening feature(s) 3405, 4405, 4407, 5409 facilities some deformation of the locking flap 3402, 4402, 5402 in an out-of-plane direction away from the retainer wall. Because of the weakening feature(s), a central portion of the locking flap 3402, 4402, 5402 is already biased to deflect slightly away from the retainer wall, i.e. a part of the locking flap 3402, 4402, 5402 is already biased in an unlatching direction. This makes it easier for a user to deflect the locking flap 3402, 4402, 5402 in the way that is necessary to cause disengagement of the latches, thereby making the latch easier to disengage. This provides an additional option for tuning the tightness of the lock. Figures 23 to 26 illustrate a package 6100 of another embodiment of the invention. Specifically, Figure 23 illustrates a flat blank 6200a that can be folded to form a sleeve 6200 of the package 6100, and Figure 24 illustrates a flat blank 6300a that can be folded to form an insert 6300 of the package 6100. Figures 25 and 26 illustrate the assembled package 6100 in the closed configuration. It should be noted that the package 6100 of this embodiment has many features in common with the package 100 of the embodiment of Figure 1, but differs in a number of ways that will be described below. Referring to Figure 23, this shows the blank 6200a that forms the sleeve 6200 of this embodiment. Similarly to the blank 200 of Figure 5 that forms the sleeve 200 of the first embodiment, the blank 6200a comprises a single continuous sheet, and includes a rear wall 6204, side walls 6206, 6208, and an inner front wall 6202 defined by inner and outer front walls 6202b and 6202a respectively. However, features of the form and configuration of the closure flaps 6250, 6250a, the first locking feature 6400 and dust flaps 6280 of the sleeve 6200 of this embodiment differ from equivalent features of the sleeve 200 of the embodiment of Figure 1. Turning first to the closure flaps 6250, 6250a, the sleeve 6200 includes a first closure flap 6250 at the first or forward end 6112 of the package 6100 and a second closure flap 6250a at the second or rear end 6114 of the package 6100. The first closure flap 6250 comprises a top cover 6252 and an extension flap 6254. The top cover 6252 and the rear wall 6204 are continuous with one another, with a fold or crease 6251 defining the boundary therebetween. The extension flap 6254 and the top cover 6252 are also continuous with one another, with a fold or crease 6256 defining the boundary therebetween. In contrast with the embodiment of Figure 1, the crease 6256 defines a curved boundary in this embodiment, such that a distance, d, between creases 6251 and 6256 is greater at a central portion of the top cover 6252 than at edges 6253 of the top cover 6252. In the assembled sleeve 6200, the curved crease defines a curved upper or front edge 6255 of the top cover 6252. As is best illustrated in Figures 25 and 26, the curved front edge 6255 improves engagement between the top cover 6252 and the front wall 6202 of the sleeve 6200 when the package 6100 is in the closed configuration. In particular, the curved shape of the front edge 6255 removes or reduces gaps or spaces that may otherwise exist between the front edge 6255 of the top cover 6252 and the front wall 6202 in an arrangement having a straight front edge profile. In this way, the likelihood of e.g. a child gaining access to the contents of the package 6100 by forcing their fingers between the top cover 6252 and the front wall 6202 and prying the package 6100 open is reduced. Furthermore, the curved profile of the front edge 6255 encourages the connecting extension flap 6254 to bend in such a way as to deflect the extension flap 6254 towards the front wall 6202 in the closed configuration, thereby improving engagement between the locking features 6400, 6500 of the package 6100. Further still, the curved profile is beneficial to improve crush strength or resistance of the package, for example in an axis extending perpendicularly to the plane of the retainer wall 6310. Referring again to Figure 23, the extension flap 6254 of the first closure flap 6250 includes a first tapered portion 6257. The first tapered portion 6257 is adjacent the top cover 6252 and is tapered in width, such that the width of the extension flap 6254 decreases moving away from the top cover 6252 and towards the locking aperture 6260. The first tapered portion 6257 leads to a second portion 6259 of the extension flap 6254 that has a width that is smaller than the width of the front wall 6202 of the sleeve 6200. In this way, when the package 6100 is in the closed configuration, small gaps are provided between side edges 6261 of the extension flap 6254 and side edges 6203 of the front wall 6202 by virtue of the reduced width of the second portion 6259 of the extension flap 6254. This allows space for the side walls 6206, 6208 of the sleeve 6200, and in particular side edges 6203 of the front wall 6202 of the sleeve 6200, to be squeezed slightly towards each other to cause deflection of the front wall 6202 away from the retainer wall 6310 of the insert 6300 to unlatch the locking features 6400, 6500 of the package 6100 and allow the first closure flap 6250 to be opened. It will be appreciated from Figures 2, 3 and 5 in particular that the extension flaps 254 of the sleeve 200 of the first embodiment of the invention include a similar tapered portion to that of the sleeve 6200 of Figures 23 to 26, but that the taper of the tapered portion is more pronounced in the sleeve 6200. This more pronounced taper allows for a greater degree of inward deflection of the side edges 6203 of the front wall 6202, thereby enhancing the useability of the package 6100 to provide a more user-friendly solution. Turning now to the second closure flap 6250a, this closure flap 6250a is configured to provide a permanent closure at the rear end 6114 of the package 6100. Thus, although the first and second closure flaps 6250 and 6250a have many features in common with one another, the form of the second closure flap 6250a differs slightly from the first closure flap 6250 to enable this different functionality. Specifically, the extension flap 6254 of the second closure flap 6250a does not include a tapered portion. Instead, the portion 6263 of the extension flap 6250a adjacent the top cover 6252 has a constant width that is substantially the same as the width of the top cover 6252, and of the front wall 6202. As such, side edges 6261 of the extension flap 6254 of the second closure flap 6250a are aligned with side edges 6203 of the front wall 6202 when the package 6100 is in the closed configuration. In this way, the side edges 6261 of the extension flap 6254 provide a barrier to inwards movement of the side edges 6203 of the front wall 6202 in the closed configuration of the package 6100. This prevents deflection of the front wall 6202 away from the retainer wall 6310 on squeezing the sides of the package 6100, and thus prevents disengagement of the locking features 6400, 6500 to provide a permanent closure at the rear end 6114 of the package 6100 that cannot be unlocked in the same manner as the first closure flap 6250. Advantageously, this permanent closure is formed without the need for additional attachment means such as glue or other adhesive. Although in this embodiment both ends 6112 and 6114 of the package 6100 include closure flaps 6250, 6250a having a curved profile that defines a curved front edge 6255 in the closed and assembled package 6100, in some embodiments it would be possible for only one closure flap 6250, 6250a to include this curved profile. For example, in some embodiments only the first closure flap 6250 defines a curved front edge 6255 profile to provide a visual indication to the user to open the package at the forward end 6112. In that case, the closure flap 6250a at the rear end 6114 of the package 6100 may be secured in the closed position using glue or other adhesive means, for example, to ensure a permanent closure. Furthermore, it would be possible for the curvature of the boundary 6256 between the extension flap 6254 and the top cover 6252 to be more pronounced, so as to increase the curvature of the front edge 6255 in the assembled package 6100, and provide a striking visual effect. In packages 6100 having a permanent closure at one end, enhanced or exaggerated curvature of the front edge 6255 of the openable closure flap may be used as an additional means to draw the user to the correct end for opening of the package 6100. Similarly to the locking flaps of Figures 20 to 22, the locking flaps 6402 of the sleeve 6200 of this embodiment each include a weakening feature or arrangement in the form of three creases or folds, 6403a, 6403b and 6403c. Each crease 6403a, 6403b, 6403c extends along the length of the locking flap 6402, i.e. from the crease or fold 6404 that acts as the boundary between the front wall 6202 and the locking flap 6402, to the locking edge 6412 of the locking flap 6402. The creases 6403a, 6403b and 6403c are arranged to fan out from the locking edge 6412 towards the crease 6404, such that the width of the weakening arrangement tapers towards the locking edge 6412. The weakening arrangement facilities deformation of the locking flaps 6402 in an out-of-plane direction away from the retainer wall 6310. In particular, the tapered weakening arrangement encourages the locking flaps 6402 to deform so as to generally follow the curvature of the front wall 6202 when a user squeezes side edges 6203 of the package 6100. This makes it easier for a user to deflect the locking flap 6402 associated with the first closure flap 6250 in the way that is necessary to cause disengagement of the locking features 6400, 6500 and unlocking of the package 6100. It will be appreciated that the shape and number of creases defining the weakening arrangement may differ in other embodiments so as to control the manner in which the locking flap 6402 deforms and deflects to aid consistent and reliable unlocking and locking of the package 6100. It should also be understood that although in this embodiment the weakening arrangement is defined by creases, in other embodiments the weakening arrangement may additionally or alternatively comprise perforations, folds, debossed or crushed portions, and furthermore in some cases the entire panel of the locking flap 6402 may be deformed. A further difference between the package 100 of Figure 1 and the package 6100 of this embodiment is that the package 6100 does not include the same arrangement of reinforcement walls 280 that connect the top cover 252 of the sleeve 200 to the side walls 206, 208 of the sleeve 200. Instead, the sleeve 6200 includes dust flaps 6280 that are joined only to the associated side wall 6206 or 6208 at a crease or fold 6282. The remaining edges of each flap 6280 are free, i.e. do not join or attach to any other portion of the sleeve 6200. The dust flaps 6280 of this embodiment function to strengthen the package 6100 without interfering with access to the package 6100. The dust flaps 6280 can be easily deflected away from the opening of the package 6100 through which its contents are accessed by a user when the first closure flap 6250 is opened for ease of access to the package contents. Furthermore, the dust flaps 6280 do not impact the position of the closure flap 6250 in the same way as do the reinforcement walls 280, which tend to urge the closure flap 250 open. Thus, the use of dust flaps 6280 in place of reinforcement walls 280 may remove the need for a user to push the closure flap 250 slightly downwards, i.e. opposite to the opening direction O of the package 6100, in order to disengage the locking features 6400, 6500. The insert 6300 of the package 6100 of this embodiment, formed by the blank 6300a shown in Figure 24, is similar to the insert 300 of the first embodiment, having many features in common both in terms of form and function. However, the insert 6300 differs from the insert 300 in respect of a couple of features, in particular the shape of the retainer locking apertures 6312, 6312a and the shape of the creases or folds 6311 that define boundaries between the retainer wall 6310 and the guard flaps 6330. Each retainer locking aperture 6312, 6312a is defined by an elongate opening that substantially follows the general shape of the locking edge 6266 and sloped sides 6267 of the locking aperture 6260 of the corresponding closure flap 6250, 6250a. Thus, in contrast with the embodiment of Figure 1, the retainer locking apertures 6312, 6312a only mirror the shape of a portion of the locking aperture 6260 of the corresponding closure flap 6250, 6250a. The creases 6311 of the blank 6300a are curved such that, when the insert 6300 is assembled, the retainer wall 6310 follow this same curvature across its width between the brace walls 6304. In this way, the retainer wall 6310 urges the locking apertures 6260 of the closure flaps 6250, 6250a towards their associated locking flaps 6402 when the package 6100 is in the closed configuration, so as to improve engagement between the locking features 6400, 6500 of the package 6100. Figures 25 and 26 show the package 6100 in the closed configuration, and illustrate instructional graphics that may be provided on the sleeve 6200. The instructional graphics include press markings 6600 that illustrate where a user should press to most easily disengage the locking features 6400, 6500 of the package 6100. The press markings 6600 are positioned towards the front end 6112 of the package 6100 so as to align with the position of the locking features 6400, 6500 associated with the first closure flap 6520. The press markings 6600 span side edges 6203 of the package 6100, so as to indicate to the user to squeeze the package 6100 at or towards the edges 6203, rather than at another position across the height of the side walls 6206, 6208. This is useful because squeezing the package at the edges 6203 produces the greatest deflection of the front wall 6202 and the locking flap 6402 for effective disengagement the locking features 6400, 6500. Although the press markings 6600 are defined by printed graphics in Figures 25 and 26, it would be possible for additional or alternative visual markers to identify the press locations. For example, in some embodiments the press markings 6600 may comprise one or more of holes, slots, perforations and/or discontinuous creases to encourage pressing in the correct locations. In some embodiments it would be possible for printed graphics to be omitted from the press markings 6600 so as to provide a subtler indication to the user regarding press position. It will be appreciated that similar instructional markings could be provided in other embodiments of the invention. Other amendments and modifications are envisaged that also fall within the scope of the claims. For example, although in the embodiments described, the locking flap is integral with the front wall and coupled to the front wall at the forward end by a fold, this need not be the case. The locking flap may instead be formed as part of a separate piece that is coupled to the front wall, or to another part of the package, so long as it is able to lie between the front wall and the retainer wall. For example, the locking flap may be coupled to an attachment piece by a fold, and the attachment piece may be coupled to the front wall, for example by an adhesive. The attachment piece may be for example a planar tab or panel. It is also envisaged that the locking flap may be coupled to the retainer wall instead of the front wall. In this case, when the closure flap is closed, the closure flap lies between the locking flap and the front wall, rather than between the locking flap and the retainer wall. Deflection of the front wall away from the retainer wall may be achieved by any suitable means. In the embodiment described, the package is configured so that squeezing the side walls of the package will cause deflection of the front wall. In alternative embodiments, the front wall could be fitted with an engagement feature such as a tab or ribbon, that can be accessed by a user from the front of the package and pulled to deform the front wall. As explained in detail above, the sleeve and insert may be formed as separate pieces, or they may be integral with each other and formed form the same piece. The insert may be of any suitable formation as long as it comprises a retainer wall that is capable of urging the latch formations into engagement. Embodiments are envisaged in which a self- supporting structure, and may for example constitute a package in its own right. In the embodiments described above, the sleeve and insert are both made from a cardboard material. However, this need not be the case. The sleeve may be made from any material that permits sufficient deflection of the front wall to allow for unlatching. The insert may be made from any suitable material, including rigid materials. For example, the sleeve may be made form a cardboard material and the insert may be made from a corrugated card, or a thermoset plastic. In the embodiments described, both the closure flaps at the forward end and at the rear end are coupled to the rear wall. However, embodiments are also envisaged where the closure flap at the rear end is provided on the front wall instead of the rear wall. Additional panels may be added to the package if necessary. For example, a panel may be added at a side of the package or a forward or rear end of the package to support a Eurohook. The reinforcement walls 280 may be omitted, or may take a different form. For example the creases 282, 284 may be omitted. The guard flaps may be omitted form one or both ends of the package. Where guard flaps are included, the access opening may be omitted, or an alternative feature may be provided to facilitate opening of the guard flap. For example the guard flap may be provided with a pull tab or ribbon. The locking aperture and the optional aperture in the retainer wall may be of any suitable size or shape. Although in the first embodiment described above the locking aperture and the aperture in the retainer wall are the same size and shape, this need not necessarily be the case. It will be appreciated that the package may be of any suitable dimensions, and the walls and panels may be of any suitable size or shape. Although the described embodiments of the package envisage access of articles stored in the internal volume from the top of the package, it would be possible in other embodiments for the support to be configured such that articles stored within can be accessed from different directions, for example from the side or bottom. The ‘forward’ end, i.e. the end that is closed off by the closure flap and through which the contents of the package are accessed, may therefore be any end of the package, as is not limited to the top of the package as shown in the accompanying drawings. It should be appreciated that various other modifications and improvements can be made without departing from the scope of the invention as defined in the appended claims.

Claims

Claims 1. A package comprising first and second walls, joined by first and second side walls, and defining an internal volume therebetween; a retainer wall locatable in the internal volume to lie against the first wall; a first locking feature arrangeable inside the internal volume between the first wall and the retainer wall; and a closure flap coupled to the second wall at a forward end of the package; the closure flap being movable between a closed configuration in which the closure flap blocks access to the internal storage volume, and an open configuration in which the closure flap permits access to the internal storage volume via the forward end; and the closure flap comprising a second locking feature configured such that when the closure flap is in the closed configuration the second locking feature is positioned inside the internal volume between the first wall and the retainer wall, such that the retainer wall forces the second locking feature into engagement with the first locking feature to lock the closure flap in the closed configuration; wherein the first wall is flexible, to allow deflection of the first wall away from the retainer wall to cause movement of the first locking feature in an unlocking direction, thereby disengaging the first locking feature from the second locking feature to permit movement of the closure flap.

2. The package of Claim 1, wherein the first locking feature comprises a locking flap that protrudes into the internal volume between the first wall and the retainer wall.

3. The package of Claim 2, wherein the locking flap is coupled to the first wall via a fold or crease.

4. The package of Claim 2 or Claim 3, wherein the locking flap comprises a locking protrusion.

5. The package of any preceding claim, wherein the second locking feature comprises an opening formed in the closure flap.

6. The package of Claim 5 when dependent on Claim 4, wherein the locking protrusion is configured to protrude into in the opening when the closure flap is in the closed configuration, to prevent movement of the closure flap from the closed configuration to the open configuration.

7. The package of Claim 6, wherein the closure flap and locking flap are configured such that, when the closure flap is in the closed configuration, a lower edge of the closure flap is located below a lower edge of the opening.

8. The package of any preceding claim, wherein the closure flap comprises a top cover that covers an open end of internal volume, and an extension flap that extends into internal volume between the locking flap and the retainer wall when the closure flap is in the closed configuration.

9. The package of any preceding claim, wherein a spacing between the side walls defines a width of the internal volume of the package, and wherein a width of the retainer wall at the forward end of the package is less than the width of the internal volume.

10. The package of Claim 9, wherein the retainer wall comprises a protrusion region having one or more side protrusions, and wherein a width of the retainer wall in the protrusion region is greater than the width of the retainer wall at a forward end of the package.

11. The package of any preceding claim, further comprising a brace coupled to the retainer wall and configured to brace against the second wall, so as to restrict movement of the retainer wall away from the first wall.

12. The package of Claim 11, wherein the brace comprises a pair of brace walls that project away from the retainer wall towards the second wall.

13. The package of any preceding claim, further comprising a guard flap coupled to a forward end of retainer wall, and selectively arrangeable to cover a forward end of the internal volume.

14. The package of any preceding claim, wherein the first wall comprises an inner first wall and an outer first wall that overlies and is coupled to the inner first wall.

15. The package of any preceding claim, comprising first and second reinforcement walls that extend between the closure flap and the respective side walls.

16. The package of Claim 15, wherein each reinforcement wall is coupled to each of the closure flap and respective side wall by a coupling crease, and wherein each reinforcement wall comprises a further crease between the coupling creases, to allow the reinforcement wall to fold when the closure flap is moved from the open configuration to the closed configuration.

17. The package of any preceding claim, comprising an outer sleeve that defines the internal volume, and an insert that is insertable into the internal volume, wherein the retainer wall is defined by the insert.

18. The package of Claim 17 when dependent on Claim 11, wherein the brace is defined by the insert.

19. The package of Claim 17 or Claim 18, wherein the outer sleeve is formed as a separate piece from the insert.

20. The package of Claim 17 or Claim 18, wherein the outer sleeve and the insert are formed from the same piece.

21. The package of Claim 20 wherein the insert is coupled to the second wall at a rearward end, such that the insert extends from a rearward end of the second wall through the internal volume towards a forward end of the package.

22. The package of any of Claims 1 to 21, comprising: a third locking feature coupled to one of the first wall or the second wall at a rearward end of the package, the third locking feature being arrangeable inside the internal volume between the first wall and the retainer wall, or between the second wall and a further retainer wall; and a further closure flap coupled to the other of the first wall or the second wall at a rearward end of the package; the further closure flap being movable between a closed configuration in which the further closure flap blocks access to the internal storage volume, and an open configuration in which the further closure flap permits access to the internal storage volume via the rearward end; and the further closure flap comprising a fourth locking feature configured such that when the further closure flap is in the closed configuration the fourth locking feature is positioned inside the internal storage volume between the third locking feature and the retainer wall, or the further retainer wall such that the retainer wall or the further retainer wall forces the fourth locking feature into engagement with the third locking feature to lock the closure flap in the closed configuration.

23. The package of any preceding claim, wherein at least a part of the package is made of a cardboard or paperboard material.

24. The package of any preceding claim, further comprising an engagement feature configured to be engaged by the user to facilitate deflection of the first wall.

25. A sleeve for use with an insert having a retainer wall to provide a latchable package, the sleeve comprising first and second walls, joined by first and second side walls, and defining an internal volume therebetween, the internal volume capable of receiving the insert such that the retainer wall of the insert lies adjacent to the first wall; a first locking feature arrangeable inside the internal volume between the first wall and the retainer wall of the insert; and a closure flap coupled to the second wall at a forward end of the sleeve; the closure flap being movable between a closed configuration in which the closure flap blocks access to the internal volume, and an open configuration in which the closure flap permits access to the internal volume via the forward end; and the closure flap comprising a second locking feature configured such that when the closure flap is in the closed configuration the second locking feature is positioned inside the internal volume between the first wall and the retainer wall of the insert, such that the retainer wall forces the second locking feature into engagement with the first locking feature to lock the closure flap in the closed configuration; wherein the first wall is flexible, to allow deflection of the first wall away from the retainer wall of the insert to cause movement of the first locking feature in an unlocking direction, thereby disengaging the first locking feature from the second locking feature to permit movement of the closure flap.