The invention relates to a substrate coated with a coating composition, wherein the coating composition has a volume solids content of greater than 30%, said composition comprising (i) at least one polycarbonate polyol; (ii) at least one hydroxyl containing polymer selected from the group consisting of an acrylic polyol, a polyester polyol and a mixture thereof; and (iii) at least one polyisocyanate curing agent; wherein the weight ratio of (i):(ii) is 9:1 to 1:9 and wherein, if present, said polyester polyol is different to said polycarbonate polyol; and wherein the substrate is selected from the group consisting of aircraft wings, wind turbine blades, rotor blades, propellers, randomes, antenaae, fan blade nose cones and high speed vehicles.