When Iran makes the news it is often that country's flamboyant and provocative president Mahmoud Ahmadinejad who finds himself under the spotlight. But the man who wields real power in Iran is not Ahmadinejad, nor was it any of his predecessors as president. Instead it is the man who has served as the head of the country's religious structure since 1989, the Supreme Leader, Ayatollah Ali Khamenei.

The Ayatollah owes his rise to power to two men - his predecessor as Supreme Leader, Ayatollah Ruhollah Khomeini and the previous president, Hashemi Rafsanjani.

Ayatollah Khamenei has been a cleric for most of his life, beginning as a religious scholar in the city of Mashhad at the tender age of 11. He served several terms in jail as a result of his religious convictions during the secular dictatorship of the Shah. His rise to power began with the revolution of 1979 that turned Iran into the Islamic Republic. Khamenei became, first president, a post with relatively little power, and his election as Supreme Leader after the death of Khomenei was a surprise to all. Many believe this was engineered by Rafsanjani to allow Rafsanjani himself to remain in control.

But Khamenei has gradually made himself the most powerful man in Iran - and he's done so by recruiting the Revolutionary Guard to his side. There are those who say that far from a religious dictatorship, Iran is in fact a military dictatorship.

But Ali Khamenei is 72 and with 70 per cent of the Iranian population having been born since the revolution, it's not clear that the post of Supreme Leader will survive his death.

Producer TIM MANSEL