Hogg and Weeks in Pistols of the World have this to say about Tranter's history:-
William Tranter was a gunmaker of considerable repute in Birmingham, and an extremely active inventor and patentee of a variety of firearms refinements. His greatest period of pistol activity was during the percussion era, but most of his work seems to have been the production of revolvers for other people, rather than for sale by his own company. Numbers of revolvers sold by 'country gunmakers' in the middle of the 19th century, and bearing their names, were made by Tranter and invariably bear the marking 'Tranter's Patent' on the frame. It also appears likely that he made revolvers of other patterns for companies without manufacturing facilities. Just to complicate the issue, it is also likely that colourable imitations of Tranter's revolvers were made, under licence, by other companies who marked their products 'Tranter's Patent' where applicable