5 A FENCE TECHNICAL FIELD 10 The present invention relates to a post and rail fence made from steel. More particularly, the present invention relates to a steel fence that includes two spaced-apart upright support posts, a top rail and a bottom rail extending between the posts, and infill panels formed from steel strip positioned between the posts and having upper and lower ends supported by the rails. 15 BACKGROUNDART Safety and cost are important issues for fences that are used, for example, to separate adjacent suburban properties and in other applications. 20 The fences require sufficient structural integrity to withstand loading, such as wind loads and children or adults climbing over fences. The requirement for structural integrity is a factor that has a direct bearing on the construction of the fences, including the steel gauge, the length of spans between fence support posts, and the profile and the size of the posts, rails and infill panels. In the final analysis, the amount of steel in the 25 fences and the structure of the components that make up the fences have a direct impact on the cost of the fences. The above references to the background art do not constitute an admission that the art forms a part of the common general knowledge of a person of ordinary skill in the art. The above references are also not intended to limit the application of the fence 30 as disclosed herein. SUMMARY OF THE DISCLOSURE The present invention provides a fence that includes two spaced-apart upright 35 support posts, a top rail and a bottom rail extending between the posts, and at least four infill panels formed from steel strip positioned between the posts and having upper and 1 3235564_1 (GHMaters) P89934.AU 5 lower ends supported by the rails, with at least one pair of adjacent panels having overlapping side edges, and a fastener securing the two overlapping panels and one of the rails together to improve the structural integrity of the fence. The applicant has found that the above-described fence with at least four infill panels and a fastener that secures two overlapping panels to one of the top and bottom 10 rails has sufficient structural strength to support wind loads and children and adults climbing the fence. The fence may include at least one fastener securing the two overlapping panels and the top rail together and at least one fastener securing the two overlapping panels and the bottom rail together. 15 The fence may include four panels, with the overlapping panels being the middle pair of panels. The fence may include a plurality of fasteners securing each panel and the rails together. Each panel may be made by roll-forming or pressing steel strip into a suitable 20 profile. Each panel may be formed from steel strip that is less than or equal to 3.5 mm gauge steel. Each panel may be formed from 3.5 mm gauge steel strip. Each panel may be made from corrosion resistant metal alloy-coated steel strip. 25 Each panel may be a profiled panel that includes a series of parallel ribs. The ribs may be any suitable profile. For example, the ribs may be open or closed ribs. The ribs may be at least 20 mm deep. The pitch of the ribs may be at least 80 mm. 30 Each panel may be at least 1700 mm high and at least 700 mm wide. Each panel may be at least 1700 mm high. Each panel may be at least 750 mm wide. The posts and the rails may be formed from corrosion resistant metal alloy coated steel strip that is less than or equal to 3.5 mm gauge steel. 35 The posts and the rails may be formed from corrosion resistant metal alloy coated 3.5 mm gauge steel strip. 2 3235564_1 (GHMaters) P89934.AU 5 Each rail may be an elongate channel with an open mouth, with upper and lower ends of the panels extending through the open mouths and received in the channels of the rails. The posts may be spaced-apart by at least 2500 mm. 10 The posts may be spaced-apart by at least 2750 mm. Each post may be an elongate channel with an open mouth, with side edges of the panels and ends of the rails extending through the open mouths and received in the channels of the posts. The fence may include a plurality of unit lengths of fence, with each unit length 15 including the above-described fence having two spaced-apart upright posts, a top rail and a bottom rail extending between the posts, and at least four infill panels formed from steel strip positioned between the posts and having upper and lower ends supported by the rails, with at least one pair of adjacent panels having overlapping side edges, and a fastener securing the two overlapping panels and one of the rails together 20 to improve the structural integrity of the fence. The present invention also provides a fence kit for constructing the above described fence that includes a plurality of the posts, rails, infill panels and fasteners. BRIEF DESCRIPTION OF THE DRAWINGS 25 Notwithstanding any other forms which may fall within the scope of the fence of the invention as set forth in the Summary, a specific embodiment will now be described, by way of example only, with reference to the accompanying drawings in which: 30 Figure 1 is a front view of a section of an embodiment of a fence in accordance with the present invention; Figure 2 is a side view of a longer section of an embodiment of a fence in accordance with the present invention that includes a plurality of the unit fence shown in Figure 1; 35 Figures 3(a) to 3(f) are perspective and cross-sectional views of the main components of the fence shown in Figure 1; 3 3235564_1 (GHMaters) P89934.AU 5 Figure 4 is a vertical cross-section through the part of the fence enclosed by the circled area of Figure 1; and Figure 5 is a horizontal cross-section that illustrates the overlap of the two middle infill panels of the fence shown in Figure 1. io DESCRIPTION OF EMBODIMENTS The embodiment of the fence 3 in accordance with the present invention shown in Figure 1 includes: (a) spaced-apart support posts 5, 15 (b) a top rail 7 and a bottom rail 9 extending between the posts, (c) four infill panels 11 positioned between the posts 5 and having upper and lower ends supported by the rails 7, 9 and adjacent panels 11 having overlapping side edges, (d) fasteners (not shown in Figure 1) securing each panel 11 and the rails 7 20 together, and (e) fasteners 13 (not shown in Figure 1 but shown in Figure 4) securing the two middle panels 11 and the rails 7 together at the overlap of the panels 11. The fasteners 13 are provided to improve the structural integrity of the fence. Figure 2 illustrates a longer section of fence in accordance with the present 25 invention. The longer fence section includes a plurality of the shorter fence section 3 shown in Figure 1. In effect, Figure 1 illustrates a unit length of fence 3, which can be repeated as required to form a desired length of fence. The main components of the fence 3, namely the posts 5, the rails 7, 9 and the infill panels 11, are illustrated in Figures 3(a) to 3(f). The profiles of the components 30 shown in the Figures are examples of a wide range of different possible profiles for the components. The Figures include examples of dimensions for some of the components. These dimensions are examples of a wide range of different possible dimensions for the components. The components are roll-formed from metal-coated steel strip. The components may be pressed or otherwise formed from steel strip. 4 3235564_1 (GHMaters) P89934.AU 5 With reference to Figures 3(c) and 3(d), the top and bottom rails 7, 9 are in the form of elongate channels with an open mouth that is shaped to receive respective upper and lower ends of the infill panels 11. With reference to Figures 3(e) and 3(f), each post 5 is also in the form of an elongate channel with an open mouth that is shaped to receive side edges of the infill 10 panels 11 and the ends of the rails 7, 9. Figure 3(a) illustrates two posts 5 fastened together to form two opposed channels. With reference to Figures 3(b) and 5, each infill panel 11 is in the form of a profiled panel forming a series of parallel ribs "X". Each rib "X" includes a base wall 15 15 and a pair of diverging side walls 17 which terminate in short flanges 21 (shown only in Figure 5). One specific example of the fence 3 has a nominal post-to-post span of 2900 mm and includes infill panels 11 that are 1800 mm high and 760 mm wide and are roll formed from 3.5 mm gauge metal alloy-coated steel strip. The infill panels 11 are 20 profiled as shown in Figures 3(a), 3(b) and 5, with the panel ribs being 24 mm deep and having a pitch of 88 mm. The fasteners may be any suitable fasteners. For example, the fasteners may be (a) self-drilling, self-tapping hexagonal washer head screws, (b) self-drilling, self tapping long drill bit hexagonal head screws, or (c) self-drilling, self-tapping hexagonal 25 head screws. Figure 5 is a horizontal cross-section that illustrates the overlap of the two middle infill panels 11 of the fence 3. Figure 4 is a vertical cross-section through the part of the fence enclosed by the circled area of Figure 1 and illustrates the engagement of the fastener 13 with the two 30 middle infill panels 11 and the top rail 7 at the overlap of the two middle panels 11. The fastener 13 penetrates one side wall of the top rail 7. There is the same engagement of another fastener 13 with the two middle panels 11 and the bottom rail 9 at the overlap of the two middle panels 11. The engagement is important in terms of providing the required structural integrity for the four infill panel fence 3 having the 35 typical dimensions, including a nominal post-to-post span of 2900 mm, described above and shown in the Figures. 5 3235564_1 (GHMaters) P89934.AU 5 The fence 3 may be installed as described below. 1. Layout stringlines to position your fence Lay stringlines to mark the outside line of the posts 5 and help to set the posts at a required height. 10 2. Layout posts and dig holes Determine the positions of the posts 5. Lay the rails 7, 9 on the ground butting end to end between the posts. For raked sites, longer rails may need to be used. If there is to be a gate, locate the gate posts. Dig the holes. 15 3. Place the first post If the ground slopes, start at the high end. Lay a minimum of 40 mm concrete under the end of the first post 5 and set the post into the hole. Fill the hole with concrete. Ensure that the concrete tapers away from the post. 20 4. Place remaining posts Place the second post 5 in its hole and engage a bottom rail 9 with the first and second post. Make sure the bottom rail 9 is 50 mm above the ground. Fasten the bottom rail 9 with one hexagonal head screw from both sides of each post. Use the stringline to ensure the posts 5 are all the correct height, plumb and in line, before concreting into 25 position. Wait at least 24 hours for the concrete to dry before installing infill panels 11. Continue installation of the posts 5 and the bottom rails 9 for the remainder of the run. 5. Preparing infill panels Start at the high side. Insert the first panel 11 flush into the bottom rail 9, usually 30 about 200 mm out from the post 5. Lift the top rail 7 and slowly slide the panel 11 into the top rail 7. Slowly ease the first sheet along the rails until it contacts the post 5. When the second infill panel 11 is placed, ensure that there is the required overlap with the first panel 11. At this stage some minor adjustments may be necessary to get the lap to sit correctly or to fit the panel 11 into the bottom rail 9. Repeat the process for the 35 third and fourth panels 11. The fourth panel 11 is the most difficult. Place the bottom of the panel 11 into the bottom rail 9, ensuring there is overlap to the third panel 11. 6 3235564_1 (GHMaters) P89934.AU 5 Once the fourth panel 11 is in position, gently tap the top rail 7 down onto the panels 11. The fence requires fasteners 13 to be engaged at the top and bottom of the middle lap of the four infill panels 11 as shown in Figure 4. The fasteners 13 should pass through the infill panels 11 into the rails 7, 9. Each fastener 13 should pass through the laps. 10 6. Fixing infill sheets to rails From one side, fasten infill panels 11 to both top and bottom rails 7, 9 with fasteners. 15 The applicant has found that the above-described fence with four infill panels and fasteners that secure the two middle panels to the top and bottom rails at the overlap of the panels has sufficient structural strength to support wind loads and children and adults climb the fence. Many modifications may be made to the embodiment of the invention described 20 herein without departing from the spirit and scope of the invention. By way of example, whilst the embodiment includes four infill panels 11, the present invention is not so limited and extends to any suitable larger number of such panels. By way of further example, in a situation where there is more than four infill 25 panels 11, the fence may include fasteners securing any suitable pair of overlapping panels to the rails 7, 9. In the claims which follow, and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word "comprise" and variations such as "comprises" or "comprising" are used in an inclusive 30 sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the fence as disclosed herein. 7 3235564_1 (GHMaters) P89934.AU