It looks to be either a mark 10 or 12, I have an original workshop manual for it here somewhere I use on my own Villiers motors. Anyhow the year is occasionally stamped on the flywheel, Now is there any way you can take the aluminum cover off the brass flywheel without undoing the main crank bolt? Reason I ask, is the flywheel isn't on a key and needs to be carefully manually timed in if you remove the flywheel....
