From an auction site, "Van Wart was primarily an agent or dealer who purchased arms in England and exported them to the American market," often to the Southern States. This might explain why there is no mention of this maker's name in any of the standard references for British-made guns. Usually a clue that a gun marked "London" was not made in London is the lack of a street address - adding the name was for marketing purposes. It looks like the barrel has Birmingham proof marks (hard to tell from the photo), which would be consistent with guns produced for an export market. This latter point is not a criticism, a great many "London-made" guns were made in Birmingham to be sold under various makers' names! Yours is a fine-looking, quality piece in very nice condition! That it made it to North America via an agent is an interesting story.
One source mentions that reference is made to Van Wart's activities in the book "THE ENGLISH CONNECTION” by Russ Pritchard, Jr. and C. A. Huey. Unfortunately I don't have this book. It is listed on Amazon, but not currently available it seems.
As to value, similar pistols, perhaps not as nice, seem to be in the $1000-1500 range, but it is really down to the buyer. Having a possible Southern/Civil War element to its provenance might increase its value to a CW collector. Perhaps another CGNer might have a copy of this book, or others on this period?
Good luck in finding a good home for this attractive pistol.
