Until Sir Mark Thatcher admitted he was involved in a plot to overthrow the government of Equatorial Guinea he was probably best known for getting lost in the Saharan desert during an ill-advised attempt at the Paris-Dakar rally
Mark Thatcher after he was rescued in 1982
With his mother at the height of her powers in Downing Street he attempted the drive with, as he himself admitted, very little preparation.
The result was a full-blown and embarrassing international rescue mission.
It was one of the few times he managed to knock his mother off the front pages of Britain's newspapers.
"The biggest story of 1982 was the Falklands war. The second biggest also involved my mother and me," he once wrote.
Born in 1953, Sir Mark inherited his late father's hereditary baronetcy in 2003.
He left Harrow public school in 1971 with just three O-levels, did not go to university and failed his accountancy exams three times.
He went through a series of short-term jobs which each lasted about a year.
He dabbled in the Hong Kong business world and built up a network of business associates from the motor racing world plus the Middle and Far East.
In 1977 he set up Mark Thatcher Racing, a car racing company which developed cash problems.
But it is his controversial business dealings abroad that have proved potentially more explosive for the Thatcher family.
Sir Mark Thatcher is reported to have a £60m fortune
In the early 1980s, he also set up Monteagle Marketing, an international consultancy firm.
In 1986 the prime minister faced questions over her son's relationship with the Sultan of Brunei.
She also faced parliamentary questions over his involvement in a contract to build a university in Oman which was revealed by the Observer newspaper in 1984.
He was representing a British company Cementation, a subsidiary of Trafalgar House, which won the contract after Mrs Thatcher urged the Omanis to give the work to Britain during an official visit.
Baroness Thatcher always denied a conflict of interests and said she had simply been "batting for Britain".
Sir Mark severed his links with Cementation and left his Downing Street flat.
Questions were also asked in Parliament over claims he received millions of pounds in commission from a 1985 arms sale to Saudi Arabia. Sir Mark denied receiving any money.
The 1980s also saw him move to the US to follow up his interests in the motoring industry, including representing David Wickins of the Lotus car company and British Car Auctions for an annual salary of £45,000.
It was here that he met and married Texan heiress Diane Bergdorf in 1987 with whom he had a son and a daughter.
In 1998 Sir Mark's business affairs came under the microscope once again, when the authorities in his new home, South Africa began an investigation into a loans scheme.
It was alleged that a company owned by Sir Mark offered unofficial small loans to hundreds of police officers, military personnel and civil servants.
When they defaulted on the loans they were pursued by debt collectors and charged 20% interest rates, according to the Star of Johannesburg.
The probe centred around whether the scheme was in accordance with lending laws.
The newspaper quoted Sir Mark as saying he only wanted to help officers in need of cash. No wrong-doing was ever proved.
It has been claimed in the press that he had amassed a personal fortune of £60m.
His later success has been attributed to shrewd investments and a series of "astute deals in Africa".