The 51 mm Light Mortar is a weapon that can be carried and fired by one man, and is found in the HQ of an infantry platoon.

The mortar is used to fire smoke, illuminating and HE rounds out to a range of approximately 750 m; a short range insert device enables the weapon to be used in close quarter battle situations with some accuracy.

The 51 mm Light Mortar has replaced the older 1940s 2' mortar.

Currently (mid 2007) the weapon is approaching its planned out of service date across the armed forces.

The capability provided by the 51 mm mortar will be replaced by a combination of systems including the 40 mm Underslung Grenade Launcher and rocket hand-fired illumination and smoke rounds. In Afghanistan, the 51 mm capability is being augmented by a purchase of a more modern 60 mm mortar.