Hi All
Ill give a bit of an update. Looking at all the info we do agree it could be a model 21. We think it could have been repainted at some point. Ive cleaned the bike and its paint work is very heavily damaged. The chain wheel also has rubbed and damaged the frame so looking at trying to remove this to assess the damage.

Information off the wheels are
Rear Wheel Hub - Sturmey AM 50 7
Front Wheel hub - Sturmey archer R 457

I hope this information can cast a bit more light. Ive also attached some pictures from the clean up process


close up of the handle bars

chain wheel

front of handle bars

Forks


Frame