If its not too much trouble, Mick, toss up the photo. Always interested.
A pic of the proof-marks on the barrel-flats would probably allow board-members to give you the info you seek.

I assume the lever in front of the trigger-guard is a Jones-patent rotary under-lever, like this:
http://www.bestgunsaustralia.com.au/indiv_guns_pages/double_rifles/alex_henry_577.htm

AH could even be Alex Henry, the original maker. Rodda sold guns in India made by a number of British (and European?) makers.