Excelsior U1 and U2 made from 1949-1954
Engine: Villiers 10D
3 speed g/b
from 1949-1952 the rear tyre profile was 2.75x19; 1952-54 it was enlargened to 3.00x19 - this could help narrow the year.
its obviously a post 1950 model, as you say (in 1950 the model adopted plungers)
All in all it looks in reasonable restorable condition. You're lucky to have most of the tinware intact - especially the front guard and tank. Have you got a toolbox for it? If it is a U1 it'll have direct lighting; if a U2 it needs a battery and rectifyer.
I expect the panel on the forward half of the tank sides would be painted cream.
Getting it licensed *shouldn't* be too hard; as long as it's clean, doesn't belch out too much smoke (so get your petroil ratio right before going to the pits) and all the lights work properly. It may be worth your while joining a classic bikes club; they can ususally help with licensing, and in the right club theyll have tonnes of information.
All I can recommend is Villiers Singles & Twins by Roy Bacon; and The Villiers Engine by B.E. Browning (which i think is out of print, so keep an eye out at swapmeets)
I hope this is any help
