Those crown ciphers are suspect to me. They are slightly different, and I don't think I have ever seen a British pistol with two ciphers on the barrel. The proofs are London Gunmakers’ Company private proof and view marks, not the government markings, so this was originally on a commercial gun not a military weapon. Officers bought their own sidearms though, so it could still have been used in military service. It is possible they were marked with the royal cipher because they were bought into the government stockpile after they had already been made; that seems unlikely to me, and the fact that there are two royal cipher stamps used also seems odd. You often see funky markings on trade guns out of North Africa and the Middle East though. Perhaps that is where the gun it was on was sent.