In 1956, Leyland Motors, which was the design parent for the Centurion Mk 7, built three prototypes of an MBT called the FV4202 aka 40ton Centurion. This was similar in some respects to the earlier Centurion but had only five roadwheels and a new turret without a mantlet, and the driver was seated reclining at the front of the hull allowing the hull's height to be reduced. Both the last two design features were adopted for the Chieftain MBT and the first mock-up was completed in early 1959 followed by the first prototype later that year. The Chieftain was first shown to the public in 1961.
An additional six prototypes were built between July 1961 - April 1962 and in May 1963 the Chieftain was accepted for service with the British Army. About 900 Chieftain MBTs were built for the British Army and production was completed in the early 1970s.