Ok, I'll come and see Ron anyway, and we will try to go on the trip to Donald Fife's chapel that Ron and Sven are organising.
Your tank is probably wartime, but the smaller one for a G3L, after 1948 the filler caps were altered for the bayonet type. It's perfectly normal for it to have been fitted after the Army rebuild, a lot of rebuilt G3's also have smaller headlamps, pannier frames etc. etc.
