I took a second look at your photos and saw, in the last photo, that the rear brake bridge is arched with very nice reinforcements. I do not think that is a feature used on Carlton bikes - perhaps if your BB sleeve matches my description, perhaps your bike is from a U.K. custom builder who sourced the bottom bracket sleeves from the same place as Carlton?
1950 Carlton Flyer - oversized aluminum bottom bracket sleeve 1967 Carlton Competition - normal bb sleeve in Nervex (your) shell.
- Don Gillies
San Diego, CA, USA