The invention comprises azo dyes which have at least one SO3H group and at least one group of formula <FORM:0952620/C3/1> where p is 0, 1 or 2, one of m and n is 0 and the other 0 or 1, X is CO, SO2, O, S or SO when both m and n are 0 and for CO or SO2 when one of m and n is 1, R1, R2 and R3 are H or hydrocarbon or substituted hydrocarbon radicles or, when n is 1, R2 and R3 can together form an alkylene radicle and Y is <FORM:0952620/C3/2> where Z is Cl or Br, the said group being attached to a carbon atom of an aryl nucleus of the dye. The dyes may be made by conventional diazotization and coupling processes, by condensing an appropriate aminoazo dye with a trihalo-pyrimidine or by introducing the said group into the dye molecule by usual methods. Monoazo dyes are preferred. Metal complexes, preferably of copper, nickel, chromium and cobalt may be made from appropriate metallizable dyes. Indicated dyes are from the azobenzene, azonaphthalene, phenylazonaphthalene, phenylazopyrazolone and naphthylazopyrazolone series. Indicated polyazo dyes are of the A --> M --> E, A --> Z \sM A1 and E1 \sM D --> E series where A and A1 are diazotizable aryl amines, D a tetrazotizable aryl diamine, E and E1 are coupling components, M a coupling component which has a diazotizable amino group and 2 a coupling component which will couple twice. A, A1 and D may contain one or more azo groups. Representative of specified values for the R's are methyl, butyl, b -hydroxyethyl, g -sulphatopropyl, carboxymethyl, b -sulphoethyl, cyclohexyl, sulphobenzyl, tolyl, naphthyl and aryl groups containing sulpho, nitro, chloro, carboxy and alkoxy groups. Representative of the linking of R2 and R3 is N,N1-divalent piperazyl. Representative of specified values for the " alkylene " residue of the above group are ethylene, hexamethylene, b -ethyl-ethylene, b -hydroxypropylene, the 1,4-divalent residue of cyclohexane, C2H4OC2H4, C2H4SC2H4 and C2H4N(CH3)C2H4. Preferably the " alkylene " residue has 1-3 carbon atoms. Amongst specified values for the said group are SO2NHCH2CH2NH, CON(CH3)CH2CH2N(CH3), SO2CH2CH2N(C6H5), CH2SO2CH2CH2N(C6H5), COCH2NH, NHCOCH2N(CH3), CH2CH2NH-COCH2NH, NHSO2CH2CH2N(CH3), OCH2-CH2NH, SCH2CH2NH and SOCH2CH2NH. Preferred classes of dyes are those of formula <FORM:0952620/C3/3> where X, Y, R2, m, R3 and alkylene are as above, E is a coupling component residue and the benzene nucleus may be substituted and their complexes with the above metals those of formula <FORM:0952620/C3/4> where R1, R3, alkylene and Y are as above X1 is CO or SO2, one R is -N=N-E (E being as above) and the other for SO3H, COOH or OH and their complexes with the above metals, those of the formula <FORM:0952620/C3/5> where R1, alkylene, R3 and Y are as above, X1 is CO or SO2 A is a monodi- or tri-cyclic aryl radicle which may contain an azo group, the -N-X1 group is preferably in the 6, 7 or 8 position and there may be SO3H in the 5- or 6-position; and metal complexes of such dyes when metallizable, copper, chromium and cobalt complexes being preferred, those of formula A-N=N-E-N(R1)-X1-alkylene -N(R3)Y, and their metal complexes, where A is as above, X1 is CO or SO2, R1, R2, Y an alkylene being as before and E being a 5-pyrazolone residue carrying a mono- or di-cyclic radicle of the benzene series in the 1-position to which is attached the NR1 group, those of formula A-N=N-E-X1-N(R2)-alkylene -N(R3)-Y1 and their metal complexes, where A, R2, R3, Y and alkylene are as above, X1 is CO or SO2 and E is a 5-pyrazolone residue with a benzene residue, attached to X1, in the 1-position and those of formula <FORM:0952620/C3/6> where A is a di- or tri-sulphonated benzene or naphthalene radicle and R2, R3, alkylene and Y are as before. The dyes colour natural and artificial textile materials, e.g. materials of cotton, viscose rayon, regenerated cellulose, wool, silk, cellulose acetate, polyamides, polyacrylonitrile which may be modified and aromatic polyester fibres. Cellulosic materials may be coloured in conjunction with a treatment by an acid-binding agent. Wool, polyamides and other nitrogen-containing materials may be dyed from a mildly alkaline, neutral or acid dyebath. Examples are provided of the preparation of the dyes and their use in colouring cellulosic textiles, a variety of colours being obtained. Provisional Specification 26767/60 relates to water-soluble dyes which contain at least one group of formula-N(R)X where R is H, or an alkyl group which may be substituted, X is a pyrimidine ring attached to N via a carbon atom and which also has at least one group of formula SO2-Z, where Z is OH, or a substituted or unsubstituted hydrocarbon or a heterocyclic radicle, provided that the dyes have at least one SO3H group. The Specification is not restricted to azo dyes. This Specification also refers to Specifications 822,047, 822,948 885,547 and 937,182.