These guns were designed to fire armour-piercing shot, small high-velocity solid rounds that were effective against tanks but did little damage to groups of infantry or soft targets like trucks.

The decision to equip British tanks with a gun capable of firing HE shells at soft targets was taken by the War Office.

The round lacked sufficient explosive power, but the power of the US 75 mm HE round used in the 75 mm M3 was found to be markedly superior and a number of Churchills used in Italy had guns scavenged from Sherman tanks and fitted to their turrets to give the Churchill NA75 (NA coming from "North Africa" where the conversions were carried out).

Vickers was working on a high velocity 75 mm gun to be fitted to British tanks.

This took the cartridge case of the 3 inch 20 cwt anti-aircraft gun mated to the US 75 mm AP and HE shell.

The weapon was used in Italy and in the Normandy invasion (and possibly in Burma against the Japanese[citation needed]) until the end of the war.