From research, I understand my stereotypical size (extrapolating from Rain) would be from 8.5UK Rain to 42.5 F last (correct?). Do any of you with a slightly high to high instep go another half size up (so in my case, to 43)?
I think this is a solid point. A solid grey flannel is on the dressier side (it's still not Super 130s, though). However, if you don't have a grey flannel, maybe I'd do that since it's more of a staple.