Judging from the one I own mate, the sizing is slightly small if your a bog standard classic medium I personally think you'd get away with a large in these.
They're Wax material so washing and general wear will cause the jacket to fade, not a bad thing just looks natural.
Ahh thats really good to know, some larges are too big and some mediums too small but by the sounds of it this should be alright.
Tarnmod you pm'd me about the thornhill, fancy a straight swap?
Accept the onset of fear and spit in the old bastards face