Welcome! This was a WW II era British Service Revolver in .38 S & W (not Special). Many of these were reimported in the 1950s and had their barrels shortened, nickel refinished and plastic stag-like stocks attached, and often bored out to fit .38 Specials. Yours seems to fit the pattern.
It was likely made in late 1942, and the .38" (bore diameter), .767 (.38 S & W case length) and 3 ton (pressure) is a proof stamping for the .38 S & W round (.38/200 to the Brits) from when it was sold commercially. Hope this is helpful.