They are Webley & Rogers "Screwgrips" per Webley & Brain patent No. 3053 of 1882. (Sometimes called "Jolly Rogers" by Scott-trained gunmakers.) Made initially by P Webley for the trade, then successor Webley & Scott. They do have back-action locks. At a time when a "best" bar-action London SLE would be 60 guineas, these might have been 50, give or take a few pounds. There are tons of guns like these out there (many Evans included), not all made to this standard of fit & finish, though.
The higher grades, with fences such as these, are (can be) excellent guns.
"These guns don't appear to be screw grips."
William Evans PairOn what basis would you say they (Wm Evans pair) are not screw-grips or, more specifically, not W&R patent guns?
