I have read that the colour change from Gray to Green was down to a German trade show, so I thought I would ask the old Wadkin employee group and this was the response.

"At the end of the 1970's Wadkin's catalogues and leaflets still all depicted machinery printed in black and white. !n 1980 they produced single machine coloured leaflets with the machinery painted green. Playing devils advacate, does anyone know for fact that some of the illustrations in the pre 1980 mono chrome catalogues/leaflets were not actually green painted anyway. In 1960 we joined the European Committee of Woodworking Machinery Manufacturers along with Germany, France and later Italy. Each had mayor international exhibitions at Hanover, Paris, Milan and Birmingham and it was decided at some point that all machinery at these exhibitions would be painted green, giving no one producer a colour advantage. The colour description from some of the exhibitors was European Green"

So it seems Wadkin joined the European Committee of Woodworking Machinery Manufactures and a colour named European Green was chosen for the members to paint their machines and I guess the Germany Exhibition was the first show where everyone painted their machine Green and we have blamed the Germans for this ever since.