I'll go along with that. I don't see any signs of anything special. The photos are not great, but I can see enough to get the feeling it's a plain factory made frame. A good English frame from the 40s-50s, such as a Hobbs, might have an oiler on the BB, pump pegs, sharper edges on the fork crown, and tabs brazed to the seat stays and fork blades for mudguard stays. I would also expect a light boss on the right fork blade. So much for what I don't see.

The fact that there's one eyelet on the rear dropout, but two on the front, suggests the builder meant it to carry a rack or basket over the front wheel. That's unusual for an English frame, so I'm thinking it's French. But what do I know.