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.

Ordnance ML 4.2 in (110 mm) mortars were slower to reach Commonwealth forces in the Pacific and Asia.

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.