Definitely a Webley from what I see. I've seen Army Navies with an additional set of Webley serial #'s on the underside of the barrels before... My evans (paradox choke) has the same action. According to Roger Lake, on a phone call, Webley had a "paradox" room in their factory at this time. They made many (most) of the ball guns and barreled actions for the trade (including lower grade hollands - we need Vol II!). I would use the same load as gungadog settled on in his Lancaster (likely webley too!), except you might has well use 2 3/4" hulls. You may substitute plastic hulls if necessary and can use standard plastic wads with the pedals cut off. Graeme Wright's book (3rd edition) has a pretty good selection of loads, but either blue dot or unique seem to stand out as the favored flavors.

The mould I recommend is from Jim Allison at CBE. It is 735-735 paradox style fosbery slug. The slugs are about .734 or so from the mould. You want the short flat point solid, not the hollow point. http://www.castbulletengineering.com.au/

Sorry about the component problems & issues down there.

Was the owner a Chilean out for Jaguar?

Good Luck.