SMLE No1 trigger put in for the fluted face: better grip or feel in someone's opinion.
Has an SMLE mag as well I see.
Peter, what I was going to say in answer about the forend has already been said!
I did have a Maltby "T" in the 11000 range that had the same MkI beech forend, and matching butt. The butt was definitely the original. Have seen photos here and elsewhere of a couple more 1941 Maltby "T"s that had the same, as well as the odd regular No4.
Shocking bit of grinding on the backsight!