nelson133:
Your girlfriend has a .38/200 British Service Revolver, manufactured between 1941 & 1943. There should be US Property stampings on it, as these were made for the US Government and supplied to Great Britain during WWII under the lend lease scheme. The markings probably are British, as the British proof tested each gun.
The British Service Revolver was chambered for the .38 S&W cartridge, the British round originally being a 200 grain lead round nose, later a 173 grain FMJ.
Manufactured on the K frame in the .38 Military & Police Model of 1905 4th Change configuration with a wartime finish and grips and a different caliber, these are a cousin of the Model 10, which is an evolution of the .38 Military & Police.
After the war a lot of these guns had the chambers drilled out to accept .38 Special rounds and were resold in the USA. Check if a .38 Special chambers, if so it should be safe to shoot with standard pressure lead loads, avoid Plus P, jacketed or +P+ ammunition. You can expect to get bulged brass as the .38 S&W is wider at the rim than the .38 special, so the bored out chambers are not a tight fit.
The markings under the crane are assembly numbers, used to track parts in the factory. These have no meaning once the gun is assembled.
The grips are probably replacements, the original grips were smooth walnut.