I take it that the bottom bracket is thoroughly Italian--that is, it accepts larger Italian cups with non-reverse threading on the drive side.

A profile photo that shows the fork rake, bottom bracket drop, and wheel clearances would be helpful. Also, a more detailed shot of the seat cluster and fork crown. The seat cluster profile suggests Raleigh Pro, but it looks like the seat stays are brazed directly to the seat tube as well as the seat lug, suggesting something else. Raleigh Pros also used Cinelli-style full-sloping fork crowns, but without stiffening tangs on the inside. And the domed treatment of the stay ends suggest British, not Italian.

If memory serves me, UK builder Colin Laing is the only builder with any volume besides Raleigh who used a "fastback"-style seat cluster