Numerically, the Humber was the most important British armnoured car in World War II, with a total of 5,400 vehicles being manufactured.
Based on a pre-war wheeled light tank design by Guy Motors of Wolverhampton, in October 1939 the Rootes Group were contracted to undertake the design and production of a new car needed urgently to fill a shortfall in Armoured car production. To save time, Rootes adopted an existing design, the bodywork of the Guy armoured car and married it to the Karrier KT4 chassis being manufactured by one of their subsidaries, Karrier, as an artillery tractor for the Indian Army. Utilising only well-tried components this presented Rootes with very few difficulties in building the new armoured vehicle and the only major changes to the existing chassis required the moving of the 90hp Rootes 6-cylinder petrol engine to the rear and strengthening the suspension. Despite production being undertaken at Karrier Motors Ltd of Luton, the name Humber (another Rootes Subsidary)was chosen in order to avoid confusion with various other military vehicles known as carriers.
The mechanical side of the Humber was relatively unadventurous; solid axles with half-elliptic springs were used, and the engine and transmission were ex-civilian truck units. Like most British-produced armoured vehicles of the time, the Humber was rugged, reliable and operationally sound. The only defect reported in service being a short engine life.
Initially the Humber was only armed with a 15mm Besa Heavy machine gun in the turret and a 7.92mm machine gun in the hull, which meant it was severely outgunned by enemy armour. It was later upgunned with an American 37mm gun in place of the 15mm Besa (Mk.IV). With a three-man crew the Humber was used extensively in the North African campaign from 1941 onwards, and was particularly liked as a command vehicle since it had more internal room than the alternative Daimler armoured car. Thereafter the Humber would see service wherever British troops were in action through to 1946.
Variants included a special radio carrier, known as Rear Link vehicle, which was fitted with a dummy gun, and an anti-aircraft version fitted with a special machine gun mounting.
The Humber gave excellent service, and was still being used by some armies in the Far East in the early 1960s.
