Grendelbean:

Nice write-up. A couple of remarks:

I think you meant Military & Police. A Regulation Police is a different, I-frame model in .38 S&W.

Also, the London proofs are post-war, post-service commercial proofs. So these were applied after the gun had been sold to a surplus dealer in Britain. You need to reverse your chronology. It went to Canada first.

The backstrap markings are interesting. Service and unit markings on WW II era revolvers are uncommon. The South Africans and New Zealanders stamped their general country IDs there. But I don’t recall seeing this kind before.