BSA Shirley Jungle Carbine Markings.

[Thunderstreak]

I have a 1945 BSA Shirley No5 Mk1. It has been in my possession for around 35 years. Finally pulled it from the safe to disassemble, clean and inspect it. It’s all matching and appears to have it’s original barrel. I have two Ian Skennerton books for reference but there are some markings on it that so far elude me.
-The unit markings on the butt stock.
-The U.C.F. marked magazine follower.
Any assistance would be appreciated!