In November 1950 the British Army issued a requirement for the FV4005 project, aiming to develop a heavy tank destroyer with extremely high firepower. The first phase involved testing the feasibility of mounting a very large gun on a Centurion tank chassis and assessing the problems caused by firing heavy ammunition.
Wickes designed a test turret that was fitted onto a Centurion Mk.3 hull. The turret could rotate 360 degrees, but the recoil from firing was so severe that safe firing was only possible in a limited forward sector.
Surviving documents show the experimental gun had a +10-degree elevation and a -5-degree depression. The FV4005 trials eventually led to one of the most famous Cold‑War tank‑destroyer projects.