Webley built a lot of boxlocks for the trade and the 20th century ones are usually built on a Rogers' pattern back-action sidelock with the screw-grip (which was patented in 1882 by Webley & Brain). the boxlock with intercepting sears is often found in guns retailled by William Evans as well as Army & Navy. Both can be very nicely finished.
William Evans boxlocks can be good value as they fetch among the lowest prices for 'London' guns - like Cogswell and Harrison do in all their grades.
A cased pair of Evans boxlock ejectors (1901) built on the Webley frame went unsold at Bonham's last week with a highest bid of £1,900 and a more highly finished cased pair (1902) built on the same frame made £5,200. I have bought Evans boxlock ejectors in need of re-jointing and cosmetic renovation for as little as £400.
Some of the double rifles retailled by Evans can be of very high quality and finish and command good prices.