And cashing in on the opportunity were Nigel Morgan, a friend of Simon Mann and Mark Thatcher, and Johann Smith, a former South African military intelligence operative.
Both Morgan, a former Irish Guards officer who worked for British intelligence and is a "registered informant" for the National Intelligence Agency (NIA) according to a well-placed intelligence source, and Smith are self-confessed "agents".
Mann and his supporters are said to be furious with Morgan, whom they accuse of treachery and betrayal, British newspapers reported recently.
They believe that it was Morgan who tipped off South African authorities about the coup, and that the authorities in turn informed Zimbabwe, resulting in the arrest of Mann and his team at Harare Airport.
After news of the release of Mann and the four South African mercenaries from jail in Equatorial Guinea broke, well-placed sources said Morgan had gone into hiding on a farm in the Free State, fearing for his safety.
Mann and his friends believe that Morgan was in the pay of Equatorial Guinea all along and was a double agent – a charge Morgan has denied.
This week, speaking to the Daily Mail from South Africa, Morgan said: "My dear fellow, intelligence is what greases the wheels of this world, and that means deceit and betrayal.
"That’s what Simon Mann was doing – deceiving the world about his intentions. It’s not illegal to plan a coup or talk about it with your chums in Annabel’s or White’s club.
"But it is in South Africa. He broke his word to people I knew, my friends, that he wouldn’t get involved in any of this. I was cornered. I had an obligation to tell what I knew," he said.
Earlier, during the mercenaries’ trial in Zimbabwe, Smith, who is known as "Peg Leg" because of severe injuries he sustained in a bomb blast during the apartheid years, admitted in open court that he had provided the British, Americans and the South African government with information about the plot.
Smith was very close to Ruben Maye, Equatorial Guinea’s minister of justice and religion, according to a former member of Executive Outcomes (EO) who was working for the company at the time of the failed coup.
The source, who has detailed knowledge of the failed coup, spoke on condition of anonymity as he fears jeopardising lucrative work commitments he has in Africa. He was still working for the company in 2003 when, he says, Chris Grové of EO travelled to Spain for a meeting with Equatorial Guinea’s rebel leader, Severo Moto.
He claimed that the meeting was arranged by Nigerian-born oil magnate Eli Calil, a close friend of both Mann and Thatcher, on behalf of the British arm of EO, Sandline, whose directors were Tim Spicer and Tony Buckingham.
Spicer, he claimed, helped with the arrangements for Grové to meet Moto, as "Sandline was particularly interested in securing oil contracts with Moto once he was put into power".
Moto then asked Grové for EO’s assistance to topple the regime of President Teodoro Obiang Nguema, promising that they would be well rewarded if they helped put him into power in the oil-rich west African state. On his return Grové reported back to the EO executive in South Africa.
But unknown to his comrades Smith – a double agent who, like Morgan, was in on the plot – warned Nguema of the planned coup. Smith’s reward was to secure very lucrative business deals and concessions for South African companies in Equatorial Guinea – including a contract for one of South Africa’s leading security companies, in which he had a share at the time.
Niek du Toit, who was released along with the other mercenaries this week, never worked for EO, but was a close friend of Lafras Luitingh, the "right hand" of the company’s founder, Eeben Barlow, and Paul Heyns.
At that stage Heyns was heading up Military Technology Services (MTS) together with Tai Minnaar, a former South African intelligence agent and a retired SADF major-general. MTS later moved in under the management umbrella of EO and shared offices with them in the Menlyn Office Park in Pretoria.
During this time MTS enjoyed a good relationship with Botswana’s Ian Khama, at the time the minister of defence, and helped train Botswana’s Special Forces. The instructors were all members of EO – and the source said, "there was no doubt that British intelligence and the British government, was aware of this military arrangement with a mercenary force".
It was also at this time that Du Toit became involved with EO. When EO ceased its official business activities, Paul Heyns moved out of the offices and carried on running MTS from his home in Wapadrand in the east of Pretoria.
Du Toit joined him at MTS as a shareholder, and they expanded the business to the supply military equipment, military training and aircraft. They also enjoyed an excellent working relationship with the Zimbabwean defence force, and with Zimbabwe Defence Industries (ZDI).
When Heyns, a Springbok aerobatic pilot, died in a plane crash in his new Ziln aerobatic plane, Du Toit inherited MTS and was firmly in charge during the period when plans for the coup began gaining momentum.
Du Toit left for Equatorial Guinea to launch businesses there as a cover for the planned coup, including opening an import/export operation, which used Russian cargo planes to ferry goods in and out of the country. He also gradually brought in specialists from South Africa as part of the plans.
The source was adamant that the South African government "never said ‘no’" to the plans to topple Nguema’s regime. The same applied to the Zimbabwean government where ZDI was poised to provide the weaponry for the coup plotters, he claimed.
But the players were also unaware of the roles of the Israeli and Moroccan governments – which both had large business interests in Equatorial Guinea – which warned Nguema about the advanced stage of planning for the coup.
It was only when Nguema began asking questions of the South African government "that people in high political places in South Africa suddenly started to reconsider their views on the planned coup."
Everybody was convinced that the coup would be successful, the source said, adding that if the Boeing carrying the mercenaries was allowed to fly from Harare to Equatorial Guinea as planned, the government would have been swiftly overthrown in a "blitzkrieg".
According to the source, one merely has to look at the two men who were first released from Zimbabwe after the Boeing with the mercenaries was prevented from taking off from Harare, "who were the two South African government spies in the group".
"It is sad that the South African government had turned a blind eye and only reacted and distanced itself from the plans for the coup once the Equatorial Guinea government officially confronted them with the information of the coup," said the source.
"The South African government could have prevented the mercenaries from leaving South Africa, but chose to let them be arrested in a foreign country."
By then, with the help of Israeli intelligence, the Equatorial Guinea government had enough information to swoop on Du Toit and his men in the country – almost simultaneously with the swoop on the plane at Harare airport.
The Boeing 727 is still stranded at Harare airport, as it cannot be flown out of the country without the necessary documentation. It is also so dilapidated that it is seen as too risky to try to get it into the air.
The owner of the plane, Bob Dodson – who is suspected of having very close ties with the CIA and operates on behalf of the agency in Africa – was never paid for the charter and apparently does not want the plane back.
He is well known in aviation circles in the US and operated his planes from Wonderboom Airport north of Pretoria.
Dodson’s Gulf Stream planes were used to fly Unita around in Angola, and he also provided a Gulf Stream as official plane in Liberia when Charles Taylor was still in power.