An oil baron said to have been at the centre of the infamous Wonga Coup in West Africa has died in a 'freak accident' at his mansion, it was revealed last night.

Ely Calil, 72, was found after apparently falling down the stairs of the multi-million pound property in Holland Park, West London. A close friend said the tycoon 'broke his neck'.

He is best known for being accused of plotting to overthrow the president of Equatorial Guinea in return for cash and oil rights – a conspiracy that also embroiled Lady Thatcher's son Mark.

The Wonga Coup was led by British mercenaries but ended in disaster in 2004 when a Boeing packed with men and weapons was seized during a stop-off in Zimbabwe.

Ely Calil (pictured) was found after apparently falling down the stairs of the multi-million pound property in Holland Park, West London

Former SAS officer Simon Mann, who led the mercenaries and served several years in African jails, said Mr Calil betrayed him.

Yesterday Scotland Yard said Mr Calil was 'pronounced dead at the scene' and, although his death was 'unexplained', there were no suspicious circumstances.

His legal team confirmed his death but said his family, including third wife Renuka, 59, and five children, would not comment.

Last night former Etonian Mr Mann said Mr Calil had failed him over the failed coup.

'He was the person who recruited me and failed to back me as he promised,' he said.

'He can't sue me now. He was ultimately dishonest. He let me down. He promised many things and failed to deliver. Ultimately that led to the coup not working.

'He was an extraordinary guy. He was very charming, very clever but also devious and manipulative. There are a lot of stories about him.'

Scotland Yard said Mr Calil was 'pronounced dead at the scene' and, although his death was 'unexplained', there were no suspicious circumstances. Pictured, Ely Calil on his wedding day with first wife Frances Condron in 1972

Mr Calil said to have been at the centre of the infamous Wonga Coup in West Africa. Former SAS officer Simon Mann (pictured), who led the mercenaries and served several years in African jails, said Mr Calil betrayed him

Mr Calil was an aggressive litigant and his lawyers forced Mr Mann to remove his name from his explosive memoir about the coup which got its name from the 'Wonga list' of alleged financial backers.

Born in Nigeria, but of Lebanese heritage and holding British citizenship, Mr Calil built a reputed £100million empire.

He diversified from the family oil mill and groundnut business into property and finance while mixing with those at the heart of British Establishment.

Operating from a £12million Chelsea mansion, and with other properties in Switzerland and Nigeria, Mr Calil was a friend of Jeffrey Archer for years.

As well as Sir March and Lord Archer, his powerful circle of friends also included former Blairite minister Lord Mandelson.

Last night former Etonian Mr Mann said Mr Calil had failed him over the failed coup. Pictured, Mr Mann in an African jail

Mr Calil was known as an aggressive litigant and his lawyers forced Mr Mann (pictured) to remove his name from his explosive memoir about the failed coup

He was invited to a Downing Street dinner hosted by the then Prime Minister Sir John Major's wife, Norma.

His friendship with Lord Mandelson drew the former Northern Ireland secretary and current European Union Trade Commissioner into the murky Equatorial Guinea affair.

And Mr Calil offered his Holland Park flat to the politician when Mr Mandelson was forced to sell his own Notting Hill home after admitting he had received an undisclosed loan from fellow minister Geoffrey Robinson.

In 2004, media reports quoted from a document in the hands of the South African authorities which claimed the businessman and politician met privately weeks after the abortive coup.

The report claimed: 'Calil says that Mandelson assured him he would get no problems from the British government side' and invited Mr Calil to come and see him again 'if you need something done'.

Both Mr Calil and Mr Mandelson categorically deny discussing the coup.

And few people had ever heard of the multi-millionaire until tragedy thrust his family into the spotlight.

Mr Calil is best known for being accused of plotting to overthrow the president of Equatorial Guinea in return for cash and oil-rights – a conspiracy that also embroiled Lady Thatcher's son Mark (pictured)

In 2003 Mr Calil's son George, the eldest of his five children and an actor in the television medical drama Holby City, was arrested following the death of his girlfriend and co-star, actress Laura Sadler.

The 22-year-old fell 40 feet from the balcony of his £500,000 flat in Holland Park after a cocaine and vodka binge.

She lay in a coma for five days before her family made the decision to turn off her life-support machine. George Calil, 33, was released without charge.

In 2006 he sold his Chelsea home, Sloane House, for an estimated £30million to Sir Anthony Bamford, the JCB chairman, before moving into a £10million rented property nearby.

Mr Calil's riches have provided a global property portfolio with homes in Switzerland and Nigeria as well as a flat behind the Science Museum in Kensington.

Despite his success, much of his business dealings remained shrouded in secrecy or overshadowed by controversy.

In June 2002, he was questioned by French police over huge payments by a French oil company to a former Nigerian dictator.

Mr Calil was accused of taking £40million in backhanders for 'fixing' a giant contract for Elf in Nigeria.

He denied wrongdoing, and was released.

In 2003 Mr Calil's son George, an actor then starring on medical drama Holby City, was arrested following the death of his girlfriend and co-star, actress Laura Sadler (left). George Calil, 33, was released without charge

He also denied involvement in the Wonga plot, despite being accused of helping to organise and fund it.

Sir Mark Thatcher was also accused of being one of its financiers.

In an interview with The Telegraph in 2008, Mr Calil broke his silence on the matter and admitted he supported a regime change in Equatorial Guinea.

However, he denied masterminding a coup and insisted he only ever backed 'democratic change' in the tiny oil-rich nation.

'There was no coup plot,' he maintained.

But he said he had financed plans by Severo Moto, the opposition leader living in exile in Spain, to return to the country.

'Severo's belief was that if he was protected in his home town and could remain alive for a few days a political storm would occur that would sweep away the present regime,' Mr Calil said.

'I am not a coup planner. I don't have a talent in that sense,' he said.

'But yes, I financed Severo Moto's political activities and yes, I introduced Simon Mann to him because of his background in security.'

'He was the person who recruited me and failed to back me as he promised,' Mr Mann said

He also admitted that Mr Mann and his mercenaries had been hired to provide military assistance to Mr Moto but said he knew nothing of the former SAS officer's plot.

'It was his lack of professionalism, his lack of discretion, his lack of judgment that caused this situation,' Mr Calil said.

But Mr Calil and Sir Mark were linked to the plot when police intercepted a letter Mr Mann had written from prison in Zimbabwe.

In the letter, he asked 'Smelly' - a nickname for Mr Calil - and Scratcher - a nickname for Sir Mark- to send 'a big splodge of wonga' (money) to help get him out of jail.

However, Mr Calil insisted that the letter did not mean the pair were being implicated, but that Mr Mann was asking his friends for help.

Mr Calil's private life – friends said he enjoyed 'the best of everything' – was equally complex.

In 1972, aged 26, he married model Frances Condron, daughter of a US tobacco magnate. They had two children.

Later he married Lebanese beauty Hayat Emma Morowa, with whom he had two more children. After their divorce, Ely married Renuka Jaine in 1989. They had a daughter.

Scotland Yard said officers were called to Mr Calil's home on Bank Holiday Monday at 8am to reports of an 'unresponsive man'.