The tragicomedy of the botched Equatorial Guinea coup enlisted two prominent cast members last week when Jack Straw, the foreign secretary, and Peter Mandelson, the European Union trade commissioner, issued denials of knowing what exactly was afoot. Once again eyes swivelled to a spectre lurking in the wings — a stinking-rich oil tycoon nicknamed Smelly who allegedly bankrolled much of the production.

It was Smelly, aka Ely Calil, who offered his west London flat to Mandelson when the then Northern Ireland secretary was embroiled in the scandal over an undisclosed loan from fellow minister Geoffrey Robinson. It forced the sale of his Notting Hill home, so he gratefully moved into Calil’s £500,000 one-bedroom flat in Holland Park.

Calil, a 58-year-old Lebanese businessman with an estimated £100m fortune and a £12m Palladian mansion off the Kings Road in Chelsea, could afford to be generous.

He was also known to nurture hopes of joining the British Establishment as a knight or lord — now an unlikely prospect as he is being sued by the Equatorial Guinea government in London and is sought by the South African police.

Back then though, cultivating Mandelson could certainly do no harm, although the latter insists he paid the market rate in rent.

Last week Mandelson denied his landlord had sounded him out over the coup plot. However, a report in the hands of the South African authorities claimed: “Calil says that Mandelson assured him he would get no problems from the British government side” and invited Calil to come and see him again “if you need something done”.

Both men vehemently denied having such a meeting, although South African police want to interview Mandelson.

The report was written by Nigel Morgan, a security consultant and former member of the Centre for Policy Studies, the Tory think tank, who interviewed Calil and had a chance to observe him.

“He was small and quite worn, looking tired and hunted,” Morgan says. “He had that swarthy Levantine look, but he’s not a flamboyant character like Adnan Khashoggi. He’s very sophisticated and quietly spoken.” Calil had no evident sense of humour. “His friends never called him Smelly to his face.”

Few people had ever heard of the thrice-married Calil before tragedy thrust him into the spotlight last year. His 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, the actress Laura Sadler, who played nurse Sandy Harper in the series. She died after “watching the sunrise” and falling 40ft from the balcony of George’s flat in Holland Park. He was released without charge.

Calil Sr has a circle of powerful friends, some of whom are now scraping egg off their faces. One is Sir Mark Thatcher, who is being investigated for his role in the coup.

His alleged nickname “Scratcher”, said to derive from his youthful eczema, came to light when it was coupled with “Smelly” in the “wonga list” of alleged plotters. Thatcher denies he is Scratcher.

Then there is Lord Archer, who is said to have known Calil since his Oxford days. Archer was asked to account for phone calls between his home and Calil on the day several conspirators met in South Africa to finalise details of their plan.