Thanks 5th, was just going by the bible and couldn't find anything with BSA & M Co marking but its quite clear in your pic.
Its a shame the date was scrubbed .......
PE, they are or were the most used rifles I own, the top two are now on collectors slots so not used much, but the bottom two go through some rounds.... regarding history the top one has had a scrape on the woodwork maybe when it was in NZ?? (the top pics don't do them justice am struggling with a new camera
Added info (tried again with camera bit better pics bit more light)