I currently wear:
US 7 C&J on 200 (chukka)
UK 5.5 G&G on MH71 (dub monk)
US7 for most other shoes, I do however feel they might be just a smidge big.
My G&G's in 5.5 are on the snugger side and thin socks are more comfortable than thicker ones, though both fit.
UK 6 in Simpson last
UK 5.5 in Rain last
...yay or nay?
From reading, Rain seems to be bigger/roomier, hence the size down.