It’s got the later Enfield “stacked EFD”.

 

It's a standard Type 4 SMLE magazine with the correct Type 3 follower. The magazine case has a BSA inspection mark below a Broad Arrow, the latter a standard mark of gov't ownership ; the follower is RFI (Rifle Factory Ishapore). Nothing rare or unusual. Correct for any .303 SMLE with an "HV" near the backsight. The "HV" indicates that the rifle has been sighted in for the Mk VII (Mark 7) ammunition; the Type 4 case /Type 3 follower was designed for that ammunition.