The 4.2 in (110 mm) mortar was a smooth-bore weapon of the Stokes pattern and was designed by the Armaments Research and Development Establishment and produced by the Royal Ordnance Factories.

The first combat use was at Second Battle of El Alamein, when the 66th Mortar Company (RE) was attached to the Australian 24th Infantry Brigade.

Australian Army units in the South West Pacific theatre were reportedly the first to receive them, before forces in Burma.

They were used during the 1950s, also by airborne artillery, deployed to Kuwait in 1961 and manned by soldiers from air defence batteries during the Confrontation in Borneo in 1965.

The normal detachment was six men and it was transported with ammunition in a 10 cwt (1,120 lb (510 kg)) trailer, usually towed behind a Loyd Carrier.