The 4 x 4 design, the "Armoured Command Vehicle, A.E.C.", 4 x 4, was indeed true to the nickname given to it by the Germans - Mammuts (Mammoths) - it was huge. Built on the very good A.E.C. Matador chassis, the armoured body could seat four officers and two radio operators. Due to its unearthly appearance and relative comfortable rear body, the vehicle was nicknamed 'Dorchester' after a famous London hotel. 416 of them were built for the British Army and the Commonwealth forces.

Used as mobile headquarters by the commanders of armoured formations, and by the Royal Signals these vehicles saw active service from 1941 onwards - including use in North Africa, Italy, and NW Europe. The body was of 12mm armoured plate on steel frames, and the vehicles weighed nearly 12 tons. The crew consisted of eight men, including the driver. Three vehicles were captured by the Germans in North Africa, with two being used by Rommel and his staff.