I only have them up to 10 for now, they go all the way up.. Width is really more of a British "F", which is a smidge bigger than our normal D. But I would go so much by that. An Alden D is different than a Ralph Lauren D. They have a G width which I may or may not regularly carry but its available.
Forgive me, Ed, I didn't really register that this was your shop. My comments must seem a bit weird!
Anyway, at the risk of teaching granny to suck eggs, just a note on what you said about width fittings: British width fittings are a motherfucker, to put it bluntly. Makers use different sizes. Some would argue that makers who use "F" as their wide fitting do so because their lasts are inherently narrower. That might be true of some, but, just in case anyone is mislead, by their own standards, British makers divide as follows:
Loake, Barker, Alfred Sargeant, Cheaney, Church's: E= Narrow, F=Medium, G = wide. Church's also do H= extra wide for some shoes
Edward Green, Crockett and Jones, Gaziano & Girling: E=Medium, F = wide, G = Extra Wide (C&J's lasts are not particularly narrow in my experience, so G is pretty wide)
John Lobb: E = Medium, EE = Wide
Tricker's: some stuff to do with numbers, I think 5 = medium!