I know almost nothing of British guns, but in the event this bit of information may add something to the conversation; I own a Fredrick T. Baker 12 bore with a Pall Mall, London address. It is a non-ejector box lock built on an Anson and Deeley action featuring Damascus barrels and very fine 100% engraving coverage. The Roman numerals in the engraving pattern date this gun to 1883, but I have no idea where the action may have been made; only that it has a London address and is high quality.