A process for the production of impregnated fibrous sheet material, which can be rolled up and stored and can be bonded to like material by the application of heat and pressure, comprises impregnating fibrous sheet material at elevated temperature with a composition which is liquid at the temperature of impregnation but solid at room temperature and which comprises a polyester resin and an unconjugated monomer having a CH2 = C < group and a boiling point of at least 70 DEG C., the monomer being present in a proportion of 4-35% by weight of the total weight of the composition. The polyester resin is derived from at least one alpha-unsaturated alpha-beta-dicarboxylic acid, one or more glycols and at least 10%, preferably at least 15%, by weight, based on the total acid and/or glycol components, of an acid component (a) and/or a glycol component (b) selected from: (a) 1,4,5,6,7,7 - hexachlorobicyclo - (2,2,1) - 5-heptene - 2,3 - dicarboxylic acid, tetrachlorophthalic acid, isophthalic acid and terephthalic acid; (b) <FORM:0836786/IV(c)/1> <FORM:0836786/IV(c)/2> and butane-2,3-diol. The polyester resin may be a mixture of two or more polyesters, but at least one polyester must contain an acid or glycol component selected as above and the other or others may or may not contain such a component, but at least 10%, and preferably at least 15%, by weight of the total acid and/or glycol components must be selected from (a) or (b) above. The preferred unsaturated acids are maleic and fumaric, but halomaleic, halofumaric, itaconic, citraconic and mesaconic acids may be used. Saturated dibasic acids, e.g. succinic, sebacic, phthalic or pimelic, polycarboxylic acids, e.g. citric or aconitic, monocarboxylic acids, e.g. lauric, monohydric alcohols or polyhydric alcohols, e.g. glycerine or pentaerythritol, may be used also. The unconjugated monomer may be styrene, diallyl phthalate or triallyl cyanurate and preferably amounts to 6-25%, advantageously 8-20%, of the composition. The composition may also contain hardening catalysts and/or inhibitors, the catalyst p being one that will cause polymerization only at and above the temperature at which the impregnated fibrous sheet material is to be bonded to like sheet material. The fibrous sheet material may be woven, netted and felted material made from non-metallic or metallic fibres or filaments, e.g. mats or cloths made from glass fibre, cotton, jute, sisal, metal gauze and cloth and wire mesh netting. Fillers may be incorporated. In a modification, impregnation is effected preferably at room temperature with a solution of the resin composition, followed by drying at a temperature of up to 80 DEG C., the solution being in a solvent which is volatile at the drying temperature and which may be another unconjugated monomer having a CH2 = C< group and a boiling point of at least 70 DEG C., or an additional quantity of the same unconjugated monomer in excess of that required in the impregnated sheet, the drying being continued until the solvent or additional monomer has wholly or partly vaporized so that the dried impregnated material contains 3% or less of the solvent or additional monomer. Solvents mentioned in the examples are acetone and vinyl acetate. Specification 746,063 is referred to.ALSO:A process for the production of impregnated fibrous sheet material, which can be rolled up and stored and can be bonded to like material by the application of heat and pressure, comprises impregnating fibrous sheet material at elevated temperature with a composition which is liquid at the temperature of impregnation but solid at room temperature and which comprises a polyester resin and an unconjugated monomer having a CH2=C< group and a boiling-point of at least 70 DEG C., the monomer being present in a proportion of 4-35% by weight of the total weight of the composition. The polyester resin is derived from at least one alpha - unsaturated alpha - beta - dicarboxylic acid, one or more glycols and at least 10%, preferably at least 15%, by weight based on the total acid and/or glycol components of an acid component (a) and/or glycol component (b) selected from: (a) 1,4,5,6,7,7-hexachlorobicyclo - (2,2,1) - 5 - heptene - 2,3 - dicarboxylic acid, tetrachlorophthalic acid, isophthalic acid and terephthalic acid: (b) <FORM:0836786/IV (a)/1> and butan-2,3-diol. The polyester resin may be a mixture of two or more polyesters. but at least one polyester must contain an acid or glycol component selected as above and the other or others may or may not contain such a component, but at least 10% and preferably at least 15% by weight of the total acid and/or glycol components must be selected from (a) or (b) above. The preferred unsaturated acids are maleic and fumaric, but halomaleic, halofumaric, itaconic, citraconic and mesaconic acids may be used. Saturated dibasic acids, e.g. succinic, sebacic, phthalic or pimelic, polycarboxylic acids, e.g. citric or aconitic, monocarboxylic acids, e.g. lauric, monohydric alcohols or polyhydric alcohols, e.g. glycerine or pentacrythritol may be used also. The unconjugated monomer may be styrene, diallyl phthalate or triallyl cyanurate and preferably amounts to 6-25%, advantageously 8-20% of the composition. The composition may also contain hardening catalysts and/or inhibitors, the catalyst being one that will cause polymerization only at and above the temperature at which the impregnated fibrous sheet material is to be bonded to like sheet material. Fillers may be incorporated. In a modification, impregnation is effected preferably at room temperature with a solution of the resin composition, followed by drying at a temperature of up to 80 DEG C., the solution being in a solvent which is volatile at the drying temperature and which may be another unconjugated monomer having a CH2=C< group and a boiling point of at least 70 DEG C., or an additional quantity of the same unconjugated monomer in excess of that required in the impregnated sheet, the drying being continued until the solvent or additional monomer has wholly or partly vaporized so that the dried impregnated material contains 3% or less of the solvent or additional monomer. Solvents mentioned in the examples are acetone and vinyl acetate. Specification 746,063 is referred to.