This work led to a War Office specification for a new tank. In effect, the FV4202 was a shorter Centurion chassis with a prototype of what would become the Chieftain turret, but armed with the 20pdr gun. Several aspects of the design were trialled by the production of the FV4202 '40-ton Centurion' with a reclined driver position and mantletless gun mounting. Leyland, who had been involved in the Centurion tank, had built their own prototypes of a new tank design in 1956. in 1954 the decision was taken that 'the next UK tank should be an evolutionary one designed to carry an HV gun with a bagged charge ammunition system'.

These involved both a development of the existing Centurion Heavy Cruiser Tank design, as well as a variety of unconventional concepts such as small 1 & 2 man tanks equipped with anti-tank missiles or auto-loading and liquid-propellant guns. Starting in 1950, a series of Concept Research Studies were undertaken 'in the search for a design to succeed Centurion'. A single design combining the firepower of the Conqueror's 120 mm gun with the mobility and general usefulness of the Centurion was seen as the ideal combination. However, the introduction of the Soviet IS-3 / IS-4 heavy tank along with Soviet T-54/T-55 led to the introduction of the Conqueror heavy tank armed with a 120 mm (4.7 in) gun. Its predecessor, the Centurion main battle tank (MBT), is widely considered to be one of the most successful of post-war MBT designs. The Chieftain was an evolutionary development of the successful cruiser line of tanks that had emerged at the end of the Second World War. It remained in service until replaced by the Challenger 1 which shared many of the Chieftain's features. A new powerpack and improved transmission gave it higher speed than the Centurion despite being heavier due to major upgrades to armour protection and the armament this allowed it to replace both the Conqueror and Centurion while performing their roles effectively. The FV4201 Chieftain was the main battle tank of the United Kingdom during the 1960s–1990s.Ī development of the Centurion, the Chieftain introduced the supine (reclining) driver position to British design allowing a heavily sloped hull with reduced height.

Challenger mk 2 main battle tank