Modified Smith and Wesson .455 in Mk II New Century Conversion revolver, 1915 (c)

During World War One (1914-1918), the demand for service revolvers outgrew production which led the British Ministry of Munitions to contract out pistol production. The American arms manufacturer Smith and Wesson were contracted to produce revolvers capable of using standard .455 inch Webley rounds. The company produced over 5,000 Mark I versions, and then a further 69,000 Mark II 'substitute standard' revolvers.

This example has been modified by having the barrel cut down.