Riss: Vi prefixed guns were produced from 1942 to 1945, yours predates September 1944 when the change over to the SV prefix occurred at serial number 769001, and is probably from 1942 or early 1943.
Technically you have a British Service Revolver, made in the same serial number range as the Victory Model and prior to that in the serial range for Militart & Police model of 1905 4th Change. Caliber was .38 S&W, with a five inch barrel.
If it is a lend lease gun it should have UNITED STATES PROPERTY or US Property stamped on it, and or GHD or WB inspector marks.