OK got good leads on British Militaria forum. Sent for the ledgers in England, and a member has an almost identical 450 NE 3 1/4 made by Rigby in 1904. All things indicate it is a pre war gun vs post war. Persistence has paid off and I'll post the info when I get it.

Talked to previous owner and was used on a Man Eating tiger hunt in India 1995 by the owner