It was the standard British/Commonwealth sidearm in the Second World War, alongside the Webley Mk IV and Smith & Wesson Victory Model revolvers chambered in the same calibre.

[2][3] While the .455 had proven to be an effective weapon for stopping enemy soldiers, the recoil of the .455 cartridge complicated marksmanship training.

[4] The authorities began a search for a double-action revolver with less weight and recoil that could be quickly mastered by a minimally trained soldier,[5] with a good probability of hitting an enemy with the first shot at extremely close ranges.

[6] By using a long, heavy, round-nosed lead bullet in a .38 calibre cartridge, it was found that the bullet, being minimally stabilised for its weight and calibre, tended to 'keyhole' or tumble longitudinally when striking an object, theoretically increasing wounding and stopping ability of human targets at short ranges.

2 revolvers to meet the military's wartime demands, and as a result Webley's Mk IV was issued as a substitute standard for the British Army.

[3] Despite officially being declared obsolete at the end of World War II, the Enfield (and Webley revolvers) were not completely phased out in favour of the Browning Hi-Power until April 1969.

[17] The Enfield No 2 is very fast to reload—as are all British top-break revolvers—because of its automatic ejector, which simultaneously removes all six cases from the cylinder.

A new .38 loading was introduced for use in combat utilizing a 178-grain (11.5 g), gilding-metal-jacketed lead bullet; new foresights were issued to compensate for the new cartridge's ballistics and change to the point of aim.

The 380/200 Mk I lead bullet cartridge was continued in service, originally restricted to training and marksmanship practice.

The Singer Sewing Machine Company of Clydebank made components but they were assembled at Enfield under their proofmarks; Singer-made parts are marked "SSM".