British QF 2-pounder gun, anti-tank.

The Ordnance QF 2-pounder (or simply "2 pounder gun") was a 40 mm British anti-tank and vehicle-mounted gun, employed in the Second World War. It was actively used in the Battle of France, and during the North Africa campaign. As tanks became sufficiently armoured to stand up to its shots, it was gradually replaced by the 6-pounder, starting in 1942, though some remained in service until the end of the war. In its vehicle-mounted variant, the 2-pounder was also a common main gun on British tanks early in World War II, and was a typical main armament of medium and heavyarmoured cars throughout the war.

Starting in 1941, the British developed the "en portee" method of mounting the 2 pounder (and later its successor, the 6 pounder) on a truck. Though only intended as a carrying method, with the gun being unloaded for firing, crews tended to fire their weapons from their vehicles for more mobility, with consequent casualties. Hence the vehicles tended to reverse into action so that the gunshield of the 2-pdr would provide a measure of protection against enemy fire.

From mid-1942, the 2-pdr was increasingly displaced to infantry anti-tank platoons, to the Home Guard units in Great Britain and to the Far East, where it was still effective against the considerably less capable Japanese tanks. It was finally removed from service entirely in December 1945. As a vehicle weapon it remained in use throughout the war. Although most tanks models equipped with it were withdrawn or upgraded to the 6-pdr, it remained in use with armoured cars.