That's an Ekla lugset, so I'd say mid to late 1940's. It might be a Carlton but from this era it could be any one of a number of British builders. All I could definitely say is that it's not a Hetchins!
Agreed, but I think Carlton is the best place to start
The frame's evidently been jazzed-up and modernised at some point, and home-spun Carlton stickers suggest that it is actually a Carlton, rather than aspirational (nobody fakes-up a carlton).
Reckon it might be a very old carlton that's been resprayed and a new decal put on it.
Here's the sort of thing I'm thinking of