The Grant was the British version of the US M3 Lee medium tank, designed concurrently with its American counterpart but with numerous alterations that were demanded by British authorities in order to be accepted into service (this following a denied request to build British tanks in the US instead). The most obvious difference was the larger turret which had thicker armor protection than that of the Lee and space for a wireless radio which eliminated the need for a dedicated wireless operator. It also lacked the machine gun cupola present in the Lee but added a smoke bomb launcher. The hull was otherwise unchanged from its US counterpart, although other unique features included sand shields and cutout tracks, the latter to replace the smooth tracks in the Lee. Although the Grant was viewed as an interim design pending the introduction of the Sherman, it nevertheless gave British forces in North Africa a noticeable firepower advantage following their introduction during the Battle of Gazala in May 1942, outgunning and outranging existing German and Italian tanks. The 75-mm gun was also highly effective against infantry using high-explosive ammunition. However, drawbacks included its high silouhette and limited traverse of its main gun, thus making it vulnerable to well-positioned anti-tank guns. Following the introduction of the Sherman, the Grant was relegated to secondary duties although many were retained for infantry support in Burma. Grants represented around one-fifth of all M3 production, although a large number of Lee tanks (unmodified aside from British radios) were also in service with the British Army.

The Grant entered production at the same time as the Lee, and its initial version, the Grant Mk. I corresponded with the basic M3 with a bolted hull and gasoline engine. This was followed by the Grant Mk. II based on the M3A5 although, confusingly, the majority were built with the Lee turret. Additionally, some M3A2 and M3A3's were also produced with the Grant turret even they did not receive a designation. Non-tank versions included the Grant ARV recovery vehicle, Grant Command command tank (one of which was famously used by General Montgomery), Grant Scorpion mine flail, and Grant CDL or Canal Defense Light searchlight vehicle. Information on British Lee variants is provided in the US M3 entry.