In reply to Jamie B:
XL generally here but I find
Rab: arms too slim so have to size up XXL and it's still tight.
Montane: XL is do-able but tight around the shoulders, and I'm bulky but not broad.
Marmot: Given it's bigger American sizes I can do L but it's a little tight across the chest/shoulders so XL generally.
Paramo: XL is billowy but I've never checked to see if L is a better fit.
Berghaus and Mountain Equipment I find similar in that XL is slightly smaller than I'd like but are okay.
Mammut: their XL is as it says on the tin. Roomy enough for underlayers but not superloose.
(note to self: you buy too much gear)