Joining together some hints already given...
I think BugBear is right, it's a generic, brand-free, standard item - though a rare one, with the swivel.
My guess is that the source is
Lancashire, though the Black Country or Birmingham are also plausible, but Andy's observation of seeing these marked Stubs helps.
Peter Stubs (1766 - 1806) was outstandingly successful in the Lancashire tool trade. His most famous products were files (where the name survives as a brand) but his company also sold a wide range of other tools, many of which were for the clock and watchmaking trade.
I don't know of much written about the Lancashire trade, except for one rather dry historical work "Peter Stubs and The Lancashire Hand Tool Industry" by E Surrey Dane. This book seems to derive mainly from the Stubs companies accounts, so is a bit skimpy on manufacturing matters, but it does explain how the trade was organised. Although Stubs had a factory where files were made, a large proportion of the lines he sold (marked with his name) were actually made by a network of outworkers, working in their own small-scale premises. A list of these includes a number who specialised in making vices, based in Rainhill, St Helens, and Warrington.
I don't know of an available pattern book showing Lancashire-made vices. The Dane book reproduces a few pages from a Stubs catalogue, confirming that the range included quite complex mechanisms for watchmaking, more exact and elaborate than the swivelling vice.
There are two modern reproductions of a Timmins (Birmingham) pattern book from the early nineteenth century, which show similar items, including one here marked as "Best Lancashire". (I mean similar in terms of construction and materials, not features.)
When I look at these, yours, BugBear's, or a similar one of my own, and try to analyse how many separate operations there would have been at the anvil and the forge, I can't help admiring the skill and doggedness of the people who made them, on piece-work, for very little money.
