A study of No.4 Mk.I "Trials" rifles: information requested!

[lmg15]

1. Serial number A 0488
2. Date (& last digit separately struck?) receiver and barrel 1930 - too faint to tell if separately struck.
3. Status (No.4 Mk.I(T) or No.4 Mk.I) Rifle is a No.4 Mk.I(T)
4. Cocking piece. SM button type.
5. Bracket (N92, JG etc.). Nil
5. Screws staked? (pad screws obviously). Yes. Pads original to rifle.
6. "T" & "TR" stamps? (added later obviously, but patterns might emerge). T stamp in middle of LH receiver wall and stamped over date on LH butt socket.
7. Original No32 number (from the buttstock if present and #s legible). Nil.
8. Proof marks. EFD barrel and receiver proof and inspection stamps. No commercial / export proofs.
9. Misc. details/notes. Nil.