
The Royal Jordanian Army expressed interest in procuring the former Shir tanks after some further modifications were made to the vehicle’s systems. However, after the Islamic Revolution in 1979 effectively forced the cancellation of the Shir 1 project, Britain hastily found a new potential buyer for the newly developed tank. The first prototype was completed and tested in 1977 while at the same time, the Iranian government placed orders for a large number of Shir 1s, as they became officially known. The modification maintained the Chieftain’s signature front hull and turret design but, among other changes, enlarged the rear of the vehicle to allow for the installation of the more powerful Rolls Royce CV12 engine.


In 1974, British engineers began work on a modified version of the Chieftain main battle tank in an attempt to fulfill a requirement issued by the Iranian Army - at the time being one of the largest foreign operators of the Chieftain tank.
