Larry,
Most of what we see in English game guns in 12 gauge is 2 1/2" 1 1/8th oz proof. Most of the English guns we find here were built prior to WWII. Few were built with 2 3/4" chambers in England, prior to the war.
Production drastically decreased after that. There were other factors involved that sent those older guns to the US, but, my original point stands. It is a nice example of a higher grade English boxlock ejector, in a level of proof, not often seen here, that is very useful to US shooters.


Best,
Ted