The Challenger I originated from an Iranian order for improved model of Chieftain - the Shir 2. The order was later cancelled due to Iranian revolution and the project was taken over by the British MoD. The design was reworked and the tank became known as the Challenger, later redesignated as the Challenger 1 and entered service with the British Army in 1983. Production ended in 1989 with a total of 420 main battle tanks produced. The Challenger 1 was phased out of British Army service in 2000 and most were sold to Jordan where it is locally known as the Al Hussein.