The L9A1 51 mm light mortar was a man-portable platoon-level mortar used by the British Army from 1988 to 2007.
The 51 mm mortar replaced the World War II-vintage 2-inch mortar in the late 1980s. It was due to be phased out by the use of the 40 mm L17A2 underslung grenade launcher (UGL) mounted on the L85A2 service rifle; however, operational experience has led to the decision to replace it with a 60 mm mortar.[1] The Hirtenberger AG M6-895 60 mm mortar was procured in 2007 as an Urgent Operational Requirement (UOR) to replace the current 51 mm mortar on current operations.[2]