The QF 6-pdr was the highly successful replacement for the 2-pdr, being copied by the Americans as the 57mm gun, M1. Its useful lifespan was extended by new developments in ammunition that improved its armour penetration capabilities allowing it to knock out heavy tanks from the flank.
 
Although supplemented by the 17-pdr, it was never entirely replaced and continued to serve in infantry units long after the war ended.