Perhaps the rifle saw use by the game department of Rhodesia or some other European coloniy? (And was stamped by the game department.)

Maybe since the rifle is not of English origin - wrong calibre and wrong proofs - it arrived in Africa in Mozambique or another non-English colony?

Maybe the rifle saw use in the Tanganyika Game dept or during WWII, and so the T stamping?

Maybe the rifle saw use in WWI for the Germans?

Lots of Maybe, eh?

JPK