I spent the day trying to fit some long cage 50's derailleurs on a '53 Hobbs.
Tried a Simplex Rigidex 35 (which turned out to be a 3 speed) and two Cyclo Benelux Tourists.
None of them could handle the 26 tooth large cog on the freewheel.
The upper pulley cage simply ran into it unless the derailleur was angled back too much.
So I switched to a 14~22 freewheel and the Benelux works, but just barely (front is 50-36).
How wide a gear range could Brits use back then? ... and how did they get it?
Amir Avitzur
Ramat-Gan, Israel