Just a heads up (I am not involved in any way) - Fieldsports magazine here in the UK (a quarterly game shooting magazine) has published a special issue on game shotguns which provides a very thorough overview of the current British market for game shooting shotguns. I picked up a copy and I feel that it is noteworthy enough to flag it up for anyone with an interest in British guns and gunmaking, international postage notwithstanding (there is also an iPad edition).

It covers Boss, Browning, Purdey, Beretta, Longthorne, Westley Richards, Perazzi, Holland and Holland, Rizzini, William Powell, Mckay Brown, Miroku, Watson Brothers, Churchill, AyA, Arrieta, Boxall and Edmiston, William Evans, Guerini, Grulla, Holloway and Naughton, Dickson; and has an article covering some of the most expensive shotguns in the world (e.g. Fabbri) and another on hammer guns.

A good read which I think you might enjoy keeping on your bookshelf.
http://www.fieldsportsmagazine.com/Fieldsports-Special-Editions/essential-guide-to-game-guns.html