It was the biggest event that the sultry little capital of Equatorial Guinea had seen since 1979, when the previous dictator, President Macias Nguema, was overthrown, tried in a cage suspended from the ceiling of a cinema, sentenced to death 101 times, then executed by firing squad.

Simon Mann, the Old Etonian mercenary accused of plotting to overthrow Macias’s iron-fisted successor, President Obiang Nguema, was spared the cage when his trial opened yesterday but the proceedings did not lack for drama – or for farce.

The prosecution said that it would not seek the death penalty for Mr Mann, a former SAS officer, but it demanded a 32-year prison sentence. It named Ely Calil, a Lebanese-Nigerian tycoon resident in London, as the mastermind of the plot. It accused Sir Mark Thatcher of being one of its chief “administrators”, who financed the aircraft and helicopter required.

It was Mr Mann’s first appearance outside the infamous Black Beach prison in Malabo since February, when he was spirited from Zimbabwe, where he had just been released after serving a three-year sentence to this tiny but oil-rich West African state.

He was clean-shaven but looked pale and gaunt and walked stiffly even given the constraints of his shackled legs. In snatched exchanges with journalists before and after the day’s proceedings he said had been treated well and hoped for clemency. But he also said he had not understood a word of the proceedings, which were conducted entirely in Spanish. Asked if he thought he would receive a fair trial he replied: “No comment.”

Mr Mann and seven lesser defendants arrived at the improvised court in a high-walled conference centre in two armoured personnel carriers protected by a truck full of soldiers.

Fearing that Mr Mann’s unindicted co-conspirators might attempt to free or kill him, the Equatoguinean authorities had more machinegun-toting soldiers ring the building, snipers on rooftops and a tank outside the gates.

Malabo hosts 15 embassies, and its diplomatic corps turned out in force – having been “invited” by the Government – flags flapping on their Land Cruisers as the rain lashed down. Even the man from the UN Food and Agriculture Organisation turned up.

The ambassadors were spared the indignity heaped on the press corps, who were stripped of shoes, watches, jewellery, rings, pens, notebooks – anything that might have been used to assassinate the chief defendant.

Mr Mann, 55, sat in the front row on a red velvet chair, staring at a three-judge panel backed by a portrait of Mr Obiang. He was the only white face among the defendants and the only one shackled. No friends or family were present. Nor were any international human rights organisations. He cut a lonely figure, and must have felt a million miles from his wife, seven children and Hampshire estate.

Two translators were sworn in but never used. The chief judge demanded that Mr Mann be unshackled and the court sat in silence until a hulking guard arrived with the key. The chief judge and the Attorney-General, José Olo Obano, then read long, almost identical statements outlining the plot to unseat their President and seize control of their country’s oil riches.

Mr Obano pointedly compared the plot with 9/11 and the terrorist attacks on Madrid and London. His Government believes that the United States, British and Spanish Governments all tacitly approved the coup attempt.

The two named Mr Calil as the mastermind but they said that Mr Mann was the person entrusted to assassinate Mr Obiang and replace him with Severo Moto Nsa, an exiled opposition leader now in Madrid. They said he was given a $15 million contract.

Mr Obono promised to produce Mr Mann’s contracts with Mr Moto, Mr Calil and Sir Mark, his force of 70 mercenaries, and the Zimbabwean agency that supplied weapons, as well as details of money transfers and calls.

For the defence, José Pablo Nvo used his opening statement to argue that Mr Mann was a “mere instrument” who was exploited by Mr Calil. He said the plot would have proceeded with or without him and urged that he be given the minimum sentence.

The proceedings were unintelligible to Mr Mann, and at one point he appeared to nod off. But near the end they were enlivened by another little drama. The judges ordered a snappily dressed Equatoguinean from the public seating to join the defendants.

It appeared that Fortunato Ofa Mbo, the Secretary-General to the Government Presidency, was also to stand trial for failing to pass on information about the plot. As Fisheries Minister, he was allegedly approached by a company in Houston employed by the plotters with a plan to take control of the coastal waters around Malabo.

The trial continues – and this long-running story grows ever more surreal.

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