The NEW WR are rebadged Turkish imports - which this not.
2-1/2" chambers means using the proper ammo, not your regular 2-3/4" ammo.
It appears to be of a set, perhaps a pair at one time with the "1" on the receiver. The single trigger is a minus.
Anson & Deeley invented the boxlock and their action design is still in use by a majority of makers. There is also the Scottish trigger plate action, WR's drop lock (which this not) and sidelocks which are altogether different.
The doll's head lockup is nice for added strength, and the maker's case is an added plus
Here is a link to what the British proof marks mean:
http://www.shotguns.se/html/uk.html
It is a 12 bore, 2-1/2" chambered and those proof marks make it appear to be from before 1954 when the marks were changed.
It looks to have been refinished, most likely before being sold at Sotheby's, probably a large estate sale/auction
I would have a pro check it out and determine what the tubes are choked.