The US property marking probably fell victim to the refinish. Your gun, which I'll assume was originally a British Service Revolver in .38 S&W and had a 5" barrel, was fully reparkerized, including trigger and hammer, which were case-hardened originally. Your gun would have shipped late 1942/early 1943. It was commercially proofed for re-sale after the war at Birmingham, as shown by the BNP stamp. The location of the British proofs is interesting, by the way; they are usually on the sides of the barrel, so this gun may have had its barrel cut before proofing.
The wooden stocks could be original; have you checked the inside surface of the right one for a possibly matching serial number stamp?
Also, what's the current caliber? Most likely, the chambers were converted for use with .38 Special ammo, easily tested by checking whether a live round will fully seat.
So overall, the gun has been extensively modified, seriously shrinking collector value, but on the other hand it is in much better shape than most of that kind we see here.