Well, M'Lud, Phoenix had 2 carriages in their catalog, albeit from the 19th century, so, a little late for a "Dennis Moore"-style scene, perhaps. But I don't know anything about the changes in design and style, so I don't know how difficult it would be to back-date them.
There was VC9, "19th Century 'Single' Brougham", which was available with either one or two horses, and VC10, "19th Century 'Hansom' Cab", drawn by a single horse (is it part of the definition of a Hansom cab that it's drawn by a single horse? I don't know). Phoenix also included a gig, VC14, and a carriage horse, VC15, though, I don't think that lends itself well to a highwayman scene, either.
Forty-Third, Ltd offer these Phoenix kits, produced today by S&D Models. They are listed in their catalog at the following webpage:
http://www.forty-third.co.uk/32_phoenix_victorian.htm
As far as I know, Mr. Gammage never had any carriages in his Rose Miniatures catalog, and the closest thing was his Egyptian war chariot, and I think he also included an ancient Briton war chariot. At least, I can find none in my Rose catalogs, but I don't have a complete set, so someone else might be able to tell us better.
Hope that helps, prosit!
Brad