Concur with Jan-Feb 1942 as the most likely shipping period. At that time, most were made in .38 S&W caliber (not .38 S&W Special) and being shipped to the British Commonwealth. And most of those had 5" barrels, as yours does. Most chambered for .38 S&W Special had 4" barrels. What is the exact caliber stamping on the barrel? Have you tried chambering a .38 S&W Special cartridge? Be aware that many of the wartime British revolvers were later (late 1950s-early 1960s) re-chambered to .38 Special. Smooth grips were used starting in early 1942, but the earlier 1930s style checkered grips like yours could be correct and original. Is there a matching serial number stamped on the back side of the right grip panel?
You could call it a pre-Victory model.