Your larger holster is for the MK VI .455 Webley. These are canvas webbing material. "Khaki" normally refers to a tan cloth for clothing. But it is also a color.

One poster above says that these are one size fits all. Sometimes, that was true. I've seen two photos of RAF and RAAF pilots with six-inch barrelled .38-200's with the butts hanging 'way out of the holsters! They must have been hard pressed to close the flaps!

The holsters specifically for the Browning 9mm were different, and came in at least two models. They have pouches for a spare magazine. And I've seen a photo of a slightly larger P-37 holster with a different fastener that was for the Colt .45 auto, a standard arm for Commando units. It otherwise looks like a larger P-37 for the .38.

It is true that the gray holsters were for RAF use. The Army had olive, and Royal Navy holsters were often white! The Royal Military Police also often used white holsters and belts. They had red caps, so you can tell them in photos, and an MP armband. I suspect that they had olive holsters and belts in combat zones.

Enlisted men in the Commonwealth forces DID sometimes have revolvers, unlike what was posted by one man above. In the case of the Webleys (.455), the leather holsters were open-topped for Other Ranks (enlisted) and with flaps for officers. I've not seen any of those Enlisted holsters for the .38's; everyone got the same holsters. (Tankers had open-topped holsters that hung low on the belt. Spare ctg. loops were sewn on the holster, which also had a place to carry a cleaning rod.)

One man above referred to a New Zealand machinegunner wearing a S&W .38. You can tell because he has the holster flap folded back, and the gun's butt is distinctive. I think it was taken during the battle for Monte Cassino in Italy.

Besides machinegunners and MP's, other enlisted men had revolvers. Dispatch riders are a good example. And Commando and other special units had handguns for all personnel. Paratroops also had a lot. The Special Air Service is the best known example of specialty troops. They could carry any sidearm available in Britain or which could be taken from the enemy.

In WW I and earlier days, officers often wore revolvers with six-inch barrels, while the issued arms for Enlisted had four-inch barrels. Officers then supplied their own weapons. But I've seen a photo of an officer and two NCO's in the Royal Household Cavalry in 1914 where all three were wearing Webley MK IV .455's, the officer's holster having a flap. (Could be MK V's, which came out in 1913. The difference was that the MK V had a slightly thicker-walled cylinder, for added safety with smokless ammo.) The officer might have had a brightly blued one, or he may have had the standard one, bought Out of Stores, as they phrased purchases from Govt. stocks. Many officers then also bought revolvers from ordinary retailers, and some, like Wilkinson Sword and Daniel Fraser, offered them nicely cased. Many preferred commercial models, like the splendid Wilkinson-Webleys or the WG model, finely finished with honed actions. And some, by WWI, carried Colt 1911 .45's. One was a politician who entered Army service after losing a post as the Naval cabinet minister. His name was Winston Churchill, and in WW II, as Prime Minister, he conceived the Commando units, based on the similar Boer Commandos whom he had fought in the Anglo-Boer War of 1899-1902. He insisted that they receive Colt .45 autos, and it was their sidearm of preference. It also took the same ammo as the Thompson guns that they frequently carried, even after the Sten replaced the Tommygun in most units. In WW I, there were leather holsters specifically for the Colt auto. They remind me of some made much later for the Spanish Star. Think of the German-made Browning 9mm holsters with a wider tip and no side flap. Mills also made canvas webbing .45 auto holsters. You can see things like this on Gunboards.com, in the British Gun Pub forum.