I don't think it is rainscald though, for one it hasn't rained whilst he's had his rug off in fact at the moment we have snow. I would have put his rug on in bad weather. The skin isn't particularly scabby more just flaky like dandruff.
I'll probably treat him for rainscald anyway and see what happens. :)
Thanks a lot for your suggestions.
'Life is not a journey to the grave with the intention of arriving safely in a pretty and well-preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming "Wow, what a ride!"'