British Tank Designation System

Tank, Infantry, Mk IV, Churchill VII (A22F). Churchill VII: Major redesign (designated A22F) with new hull and turret and 75mm gun; 1944 production. Main type in service in early post-war years.

The Churchill was of composite construction consisting of an inner skin of tin mild steel with an outer covering of armour plate bolted or riveted in position. Initially a cast turret was fitted, but later models had larger turrets of either cast, welded, or composite construction. The engine and drive were at the rear, and the overall tracks with small sprung bogie assemblies allowed space between the lower and upper runs of track for stowage of ammunition and stores, making the Churchill an unusually roomy vehicle. Escape doors for the crew were fitted in each side. Transmission featured the new Merritt-Brown four-speed gearbox which provided controlled differential steering, the Churchill being the first British tank to have this.

Armament of the Mk I was a 2pdr with a 3in howitzer in the hull front. Changing tactical requirements, however, led to a change of armament through the Churchill's production life. In common with the British cruiser tanks a 6pdr gun was fitted in 1942, necessitating a larger turret (Mk III). Experience in the desert fighting of 1941-42 led the War office to believe that speed and reliability were more important than heavy armour, and it was decided to cease Churchill production in 1943 when the A27 series of cruiser tanks became available. However, the Churchill's first combat actions, with the 1st Army in the Tunisian campaign, proved most successful in the hilly conditions of the terrain and this earned the vehicle a reprieve. In 1943, the Churchill was again up-gunned (Mk VII) with the new British version of the 75mm gun. At the same time major design improvements were effected. Since it was built to meet British railroad loading guage restrictions, the Churchill suffered from the same disadvantage as other contemporary British designs in that it was too narrow to take the larger turret required for the 17pdr gun. Thus by 1944-45 it was under-gunned by German standards, but this was offset to an extent by the vehicle's heavy armour protection. 

The other factor which made the Churchill one of the most important British tanks of 1939-45 was its adaptability to the specialised armour roles needed for the invasion of Europe in 1944. The vehicle's roomy interior, regular shape, and heavy armour made it particularly useful as an armoured engineer vehicle, bridgelayer or recovery vehicle.

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In the period of World War I, tanks were designated simply by mark numbers, for example 'Tank Mk I'. The terms 'male' and 'female' indicated gun armament in the former and machine-gun armament in the latter: 'hermaphrodite' was used in cases of mixed armament. Modifications to the basic designs, which were relatively infrequent, were denoted by the addition to the basic designation of a number of stars — Tank Mk V**', or Tank Mk V with two modifications. When the medium tanks appeared, the different models were indicated by letters of the alphabet, 'Tank Medium Mk A'. Some names — 'Whippet' and 'Hornet' for example — were semi-official and somewhat loosely used. From 1920 the Army used a somewhat similar form of designation, although the types changed. Sub-letters were used to indicate modified variants of the basic pattern: 'Light Tank Mk VIIc'. The manufacturer's name frequently appeared in everyday usage ('Vickers' Light Tank Mk II'), but this was in no way officially sanctioned. In addition to the foregoing systems, each design emanating from a War Office requirement received an ordnance designation in the A series, starting in 1926 with the A1 'Independent'. Prototypes or design variants had an E-suffix to denote stages of development or modification, thus: A14E2. The early light tanks were designated in a separate L-series. In some cases the A-series prefix was incorporated into the army terminology, for example 'Cruiser Tank A13 Mk I', which was also the 'Cruiser Tank Mk III'. By 1940 designs were being produced at a fast-growing rate and names were therefore added to certain designs to prevent undue confusion. Thus the 'Cruiser Tank Mk V later became known as the 'Cruiser Tank Mk V, Covenanter'. 

Sub-variants further added to the confusion, leading to such designations as the 'Cruiser Tank Mk V, Covenanter Mk III'. By 1942 the old system of type marks was displaced by that of type names; hence the 'Cruiser Tank Mk VIII, Cromwell Mk II' became the 'Cruiser Tank, Cromwell Mk II'.