There are many clues I've picked up over the years as to why this one is pre-war. In the Lee Speed book, I'm devoting a whole chapter on how to date these rifles, with a detailed flowchart (too much to go into here on the forum).

One clue is just as our friend old_rifle_nut said: the lack of the a wartime BM mark. Even though it's not in the photo, I'm confident it's not there. But an easier clue is simply that BSA did not make the No 1 Pattern after the war. I know this from unpublished BSA records.

As for patents, don't rely on that, because you're starting from the wrong premises.

englishman_ca, you and I need to catch up on some related matters; I'll send you a PM.

Cheers everyone!

And this is a nice looking Lee Speed BTW. Well done.