On 25 November, Sir Mark Thatcher faces a daunting appearance in a South African court on charges that he helped fund a military coup in the West African state of Equatorial Guinea. If found guilty he could face 15 years in a South African prison.
Sir Mark denies having knowingly helped finance the coup
The Money Programme has travelled to Africa to investigate the full story of the attempted coup and the men who led it. What was Sir Mark's role, and how much did he really know?
Sir Mark's business career has long attracted controversy, and rumours have persisted about the true source of his money.
After a series of controversial business deals in Europe, the Middle East, the Far East and the USA, in 1995 he settled in Cape Town.
It was here that he met another British expat, former SAS officer Simon Mann, and this was the friendship which would lead to his current predicament.
Mr Mann had extensive military experience, and drew on it to set up a private security company called Executive Outcomes. Last year he was presented with a potentially lucrative business opportunity.
The small west African country of Equatorial Guinea was previously best known as the model for Frederick Forsyth's thriller, The Dogs of War.
Since the mid-1990s, however, large oil reserves have been discovered there.
In less than a decade, the country has become one of the richest per head of population on the African continent.
The dictatorial President, Teodore Obiang, came increasingly under the spotlight of human rights groups.
With only a small army, President Obiang's regime began to look vulnerable.
According to an account given by Mr Mann, in early 2003 he agreed a plan to provide military support to escort the opposition leader in exile, Mr Severo Moto, back to Equatorial Guinea and take over as President - in effect a coup.
Sir Mark could face a jail sentence of 15 years
A contract between the two men indicates large fees would be paid to Mr Mann if the operation was successful.
The coup plot was put into action, and Mr Mann contacted a number of former mercenaries to assist him in securing soldiers and arms.
As Johann Smith, a former South African special forces soldier with good contacts amongst the mercenaries, told the Money Programme:
"The initial payment was $3,000 per man, and after the successful overthrow of President Obiang, each one would have received $30,000 and obviously employ afterwards because they would have then served as the presidential guard of the new president of Equatorial Guinea, Severo Moto."
By the beginning of this year, the operation was taking shape. It was then that Sir Mark's name first appears in connection to those implicated in the plot.
In January 2004, Sir Mark, acting on the advice of Mr Mann, invested $274,000 in a new company running an air ambulance business in West Africa.
The company was called Air Africa Ambulance, and one of the countries in which it would operate was Equatorial Guinea.
Mr Mann assured Sir Mark that the boss of this new company, one Crause Steyl, would be a good business partner.
Mr Steyl already had a successful air ambulance business in South Africa, and investors in his new scheme could expect a good financial return.
What is unclear is whether Mr Mann also told Sir Mark that Mr Steyl had been his pilot on some of his mercenary operations in the 1990s.
Sir Mark's lawyers state that their client had no knowledge of any coup plot.
By the beginning of March, hundreds of thousands of dollars had been paid into Mr Mann's offshore bank account, and he and the plotters were ready to go.
One of the payments from a certain JH Archer was for $134,000.
Lord Archer's lawyers have said that he had no prior knowledge of any coup, and never met or communicated with Mr Mann.
Another payment for $100,000 was received from Air Africa Ambulance - Mr Steyl's company, in which Sir Mark had invested.
Whether or not Sir Mark knew anything about the payment, it was this transaction that would land him in trouble.
While the plot was about to go into action, rumours about a coup were circulating.
Lafras Luitinth, a former colleague of Simon Mann, was surprised that those behind the operation were still planning a coup at all.
"The biggest mistake was to do it. The second biggest mistake was while trying to do it that there was no security - that everybody knew about it.'
D-day was 6 March 2004. Mr Mann and two colleagues waited at Harare airport in Zimbabwe to rendezvous with a plane carrying 64 mercenaries.
Before they could load the aircraft with weapons, they were arrested in a sting operation carried out by the intelligence agencies of Zimbabwe, South Africa, and Equatorial Guinea.
Although Mr Mann claimed there was no coup plot, and that he was trying to buy the arms for a security operation in Congo, he was given a seven year sentence for illegally obtaining arms.
The other mercenaries are each serving a year in jail.
In a letter leaked from his Zimbabwean prison cell, a desperate Mr Mann begged his friends to help him.
"It may be that getting us out comes down to a large splodge of wonga," the letter said.
It also referred to "Scratcher" - thought to be an unkind nickname for Sir Mark from his schooldays, when he suffered from acne.
Shortly after Mr Mann's arrest, Sir Mark's business associate, Mr Steyl, turned himself in to the South African authorities.
The authorities wanted to ask Sir Mark about his involvement.
In August he was arrested at his Cape Town home and charged with assisting in an attempt to stage a foreign coup.
His bail of £165,000 was paid by his ever-loyal mother, and he faces a court hearing next week.
If found guilty of being involved in the attempted coup, he could face a jail sentence of 15 years.
On 17 November 2004, mercenary pilot Mr Steyl pleaded guilty to involvement in the coup plot, and will be a witness against his former business partner Sir Mark.
The story of the coup that never was could yet prove to be the biggest scandal in Sir Mark's controversial business career.
The Money Programme: Mark Thatcher and the Dogs of War was broadcast on Wednesday 17 November at 1930 on BBC Two.