[quote name=AlienFTM;197684It's also worth remembering that Challenger 1 derived from a very lucrative project to sell upgraded' date=' tropicalised Chieftains to the Shah of Iran as Shir Iran ("Lion of Persia"), which was dropped when the Shah learned he could have tanks with Chobham armour. 1200 of these were built and called Shir Iran 2, but they never made it to Iran before the Shah was overthrown, there was no way on earth that the Ayatollas were getting them and so these 1200 unsold tanks were issued to the RAC as Challenger, so that in reality Challenger 1 is an evolution of Chieftain, further blurring the line between where Chieftain stopped and Challenger started. And of course Chieftain continued to evolve separately from the Shir Iran project.
Family of vehicles:
Iran did have Chieftain ( some of which also ended up in Jordan courtesy of Iraq (its a long story)
Chieftain with a CV12 and TN37 power pack became Khalid - and they all (except one) went to Jordan after the Ayotollas scrapped the contract for the upgraded tank fleet.
Challenger 1 was the next step using the CV12/TN37 fitted "new" vehicle - which had very few common components with Chieftain (albeit it was intended to have the same Fire Control System IFCS - or as fitted to Cr1 CSS. While work had commenced for Iran it wasn't that far down the line so FV 4030 ended up with numerous prototypes (the SP variety) and these were still in use while we undertook CHIP/CAIP upgrade work for Chieftain and Challenger funded by the UK and definitely not Iran. After further development 420 Cr1 were built at Leeds - Regiment 7 vehicles (reg plat XX.KG.XX) were ordered as new build from Vickers while the rest had been ordered from RO (same place different name). Early builds did not have TOGS but these were added as they became available. Cr1 ended up with 3 Marks - but post Gulf War 1 the mix and match approach means its difficult to see what started where.
The Chieftain ( which looks very good) is a "StillBrew" vehicle - ie with Armour developed by John Brewer on behalf of the then MGO General Still.