Re: Webley .577 6 shot revolver
Welcome to the forum, and you have a valuable heirloom!
However, there's only one Webley marked example known, and despite what Dowell's book and 20th century remnants of Webley & Scott said, they are a Tranter design, and the cylinder backplate should be marked: "Tranter's Patent" and " Braendelin's Improvement."
Your pics aren't clear enough to be certain, but it may have been refinished at some point. Even so, value would be in $5000 range, and maybe double that if original.