Thanks for that - I have emailed Annice and will let you know how I go.
Regarding numbering, I'm not sure that Norton did actually begin again after the war. Certainly the 20xxx used for 1920 engine numbers disappeared, but I don't know the first number of the new series! It may have been close to a match for the frame number. The motor I found for my bike is 4812, which I suspect is around 1922, and the motor in this thread is 2580. From the scant survivors, it seems likely that Norton frames were numbered sequentially from "the beginning" - that 3007 is an early 1920s frame number is a reminder that Norton were a very small manufacturer in the early days. Bob Holliday suggest fewer than 100 machines were built in 12 months in the early days of WW1. I'd love to hear the story of early Norton numbers from someone who really knows!!