Serial number indicates 1940-1945. Obviously built in Germany shortly before the war, and merely retailed by Rigby in the UK. The "Not English Make" British proof marks, and case length mark are consistent with British proof of a foreign piece between 1925 and 1955. Rigby was at the Sackville address 1908 to 1955. Many people just don't realize how much pure retailing many of the British gunmakers actually did.

Entire rear sight assembly is a poor replacement. Looks like Rechnagel. The folding leaves don't lay flat, and the original wasn't made that way. I see what he means about the restock maybe being done by Rigby California. Poor, highly inappropriate American restock. Replacement trigger maybe? In good original condition, or even correctly refinished and restocked, it would have been worth at least quadruple the current bid. The cartridge was introduced in 1911 and British Rigby had sold less than 150 by 1991. Even as it is though, it's still ten times the rifle any Ruger will ever be.