I have a strong suspicion Hilary replied to his email. But what do I know.

Anyway, Velognome, I would wait until you have the bike, then try (1) Formicaman's suggestion, then (2) Neal's suggestion, then (3) come borrow the wheelset from my Alvin track bike. It's pretty much just what you need, but 36/36. Dunlop Special Lightweight, 26 x 1 1/4, and since they were used on a track bike there is no rim wear from brake shoes. There is a hop in the rear wheel but this could be dealt with. I am not sure I want to liberate them from the Alvin (since it's all original) but I am susceptible to persuasion. Alternately you can borrow the wheels from my Schwinn New World, same size but with that famous Schwinn feature of road-hugging weight.

I will tell you that on my Fothergill I first used 27 x 1 1/4 wheels and later switched to 26 x 1 3/8. This entailed a change in brake calipers, but other than that it was not a big deal.

Not asking what bike this is for. Really. I'm not. Honest. But what hubs are you planning to use? I especially need to know the drillings, i.e. 36/36 or 32/40. If 32/40, I repeat my suggestion you go with 26 x 1 3/8, because Sun CR18's re the only modern rim available in 32/40, and only in that size.