Mr. Bambridge is the Middlemarch horse dealer; he's kind of a scumbag. Think stereotypical used car salesman of the nineteenth century. He always hangs around the Green Dragon (the dive bar and pool hall in Middlemarch). Fred Vincy falls into his debt and drags Caleb Garth down with him. Bambridge is also the guy who finds out about Bulstrode's past from Raffles at a horse fair later on in the novel.