The caliber of .38 S&W CTG suggests you have a 38/200 British Service Revolver . . . and I believe the barrel length (from tip of muzzle to front face of cylinder) will measure 5".

Although basically a S&W Military & Police model, the BSRs were made for the British Commonwealth countries during WWII and chambered for their 38/200 ammunition (we know it as .38 S&W). The original 38 S&W chambering is not interchangeable with 38 Special . . . although many of these were modified after the war to use 38 Special.

If those target grips don't remove easily with that badge on the bottom, look on the rear face of the cylinder on the outside edge for the serial number. Also check the bottom flat of the barrel (visible with the cylinder open) for that same number. They will likely begin with the letter "V" and be the same as the official serial number which appears on the butt of the steel frame under those grips.

Russ