The following information comes from The Book of the Pistol and Revolver by Hugh B. C. Pollard. The Book of the Pistol and Revolver is also available to purchase in print.
List of Some British Gunmakers
This list is compiled from various sources, such as Directories, Patent Records, books, etc., and gives merely the date at which a certain maker was at work. It does not necessarily mean that this was the first decade of his existence, and is compiled merely as a guide to the approximate dating of old weapons.