I have a Le-nfield .22, but min is marked simply
LONG BRANCH
.22"
1944
I believe that the official designation for the Rifle, .22", C Number 7 did not come in until after the War.
My rifle, I know for a fact, was built in the Armourers' Shack at the Nationals in Ottawa, back about 1961. To date, it has had close to 100 rounds through it; I don't think I'm going to wear it out at this rate. It is marked only with the initials of the man who built it.
It is accepted that Long Branch made a production run of.22" rifles in 1943; there are a few around. Considering the NEED for such rifles at that time, it makes sense that a few pilot rifles could have been made with Number 4 markings, using unnumbered Bodies from regular production nd extemporising, if you will, a needed rifle prior to the laying-down of an official Pattern.
The rifle would need to be examined by someone with a lot more knowledge concerning these things than I possess.
I would suggest posting a series of good-quality close-up photos of details of the rifle here and also in the Lee-Enfield forum over at Milsurps dot com. Between these two locations, you will be able to get opinions from MOST of the people who really KNOW these Canadian rifles.
They sure shoot nice; I will say that much for sure!