The Webley Mk IV served alongside a large number of other handguns, including the Mauser C96 "Broomhandle" (as used by Winston Churchill during the War), earlier Beaumont–Adams cartridge revolvers, and other top-break revolvers manufactured by gunmakers such as William Tranter, and Kynoch.
The standard-issue Webley revolver at the outbreak of the First World War was the Webley Mk V (adopted 9 December 1913 and remained so for the duration of the First World War, being issued to officers, airmen, naval crews, boarding parties, trench raiders, machine-gun teams, and tank crews.
The Mk VI proved to be a very reliable and hardy weapon, well suited to the mud and adverse conditions of trench warfare, and several accessories were developed for the Mk VI, including a bayonet (made from a converted French Gras bayonet), Demand exceeded production, which was already behind as the war began. Rexach & Urgoite was tapped for an initial order of 500 revolvers, but they were rejected due to defects.
This forced the British government to buy substitute weapons chambered in .455 Webley from neutral countries. and the Pistol, Revolver, Old Pattern, No.2 Mk.1 was by Trocaola, Aranzabal y Cia.. Owing to a critical shortage of handguns, a number of other weapons were also adopted (first practically, then officially) to alleviate the shortage.
The London Metropolitan Police were also known to use Webley revolvers, as were most colonial police units until just after the Second World War.An armourer stationed in West Germany recalled (admittedly tongue-in-cheek) that by the time they were officially retired in 1963, the ammunition allowance was "two cartridges per man, per year." This lack of ammunition was instrumental in keeping the Enfield and Webley revolvers in use so long: they were not wearing out because they were not being used.The Webley Mk IV .38 revolver was not completely replaced by the Browning Hi-Power until 1963, and saw use in the Korean War, the Suez Crisis, Malayan Emergency, and the Rhodesian Bush War. 2 Mk I revolvers were still circulating in British Military service as late as 1970.There may still be some police units with Webley Mk IV revolvers that, whilst not issued, are still present in the armoury.The Ordnance Factory Board of India still manufactures .380 Revolver Mk IIz cartridges, At the end of the First World War, the British military decided that the .455 calibre gun and cartridge was too large for modern military use and—after numerous tests and extensive trials—that a pistol in .38 calibre firing a 200-grain (13 g) bullet would be just as effective as the .455 for stopping an enemy.