I have a number of problems with what I can see.
First the hallmarks. I can't see a town mark which is very unusual (unless it's elsewhere on the case with another set of marks). The date letter (so far as I can make it out) is a cursive "D" and the only ones I can find like that are the Chester marks for 1729 and 1904, neither of which could be right for this watch. The maker's mark HW can only be for Henry Webb, a London maker who registered the mark from 1847 to 1879, and that date range could be about right for the watch.
Next, there is no maker's name on the movement (or on the dial, I assume). That is unusual for an English watch, and even more unusual for an alleged "chronometer". The use of the words "patent chronometer" on a watch without substantiation are, in my limited experience, exclusive to Swiss watches; more often than not the word "chronometer" has been used on such watches more in the literal sense than in the horological sense.
Do you see anything in the movement that suggests this is a horological chronometer?
It would be interesting to see photos of the dial and other parts of the case, to get a feel for the general quality of the watch.