A protective crosslinkable coating composition comprising modified epoxy resin and crosslinker the modified epoxy resin being the reaction product, by weight, of i) from 80 to 99.9 parts of di-epoxy resin of epoxy equivalent weight from 500 to 5000 and formed from the reaction of bis phenol A diglycidyl ether and bis phenol A and ii) from 0.1 to 20 parts of reactive material characterised in thata) the di-epoxy resin contains minor amounts of resin components of molecular weight less than 1000 Daltons, and the reactive material comprises b) mono-functional organic material of molecular weightat: least 100 Daltons having one moiety capable of reacting with the epoxy moieties of the di-epoxy resin and c) dicarboxylic acid of molecular weight less than 300 Daltons having two moieties capable of reacting with the epoxy moieties of the di-epoxy resin.