I have the Singleton loafer in both chocolate suede and brown burnished calf. Love them.
I believe the loafers are on the 2 last. I find them to be more narrow in the toe area than the 5 last, and a bit shorter as well. For me, the heel fits about the same on the 2 and 5 lasts. I have a bit of a higher instep, and the vamp fits well after a few wears and my foot sinks more into the cork footbed. However, I wear an 11.5D in both sizes. YMMV.