Sir Mark Thatcher: How 'the charmless Mark' pocketed a fortune trading on his mother's name

Sir Mark Thatcher once leapt to his mother's defence when questioned over her unflagging opposition to sanctions in South Africa, remarking, "my sympathy is with the struggling white community".

She in turn used to joke that she sent him there during adolescence "to clear up his spots". Perhaps it was unsurprising then that when the investigations into his business dealings in the United States became a little too intensive, he would turn his back on "the Texas crap" and build a new life for his family among the bougainvillea-draped mansions of Constantia, one of Cape Town's most prestigious suburbs.

Sir Mark and his family took up residence behind the imposing security fences of their £2m mock Tudor mansion in 1995. Here they could count among their neighbours Earl Spencer, the brother of Diana, Princess of Wales.

During the apartheid years, the Cape may have attracted a certain kind of British visitor, one prepared to see only the natural beauty of the place rather than the injustice of the racist state. But since the release of Nelson Mandela, the rich there can enjoy the world-class vineyards, the Royal Cape Golf Club and the spectacular views of Table Mountain, untarnished by associa- tions with apartheid.

During Sir Mark's journey to the tip of Africa, he is said to have amassed a fortune of £60m, a figure he claims is hugely overstated.

Born on 15 August 1953, he and his twin sister Carol were delivered by Caesarean section while their father, Denis Thatcher, a successful oil man, watched a Test match at the Oval.

The twins were completely different in temperament: Carol, outgoing and friendly; Mark introverted and serious.

Educated at Harrow, he passed just three O levels, living up to the nickname "Thickie". Failing his accountancy exams an impressive three times, he toyed with a number of possible careers. There was a job with a stockbroker, which took him to South Africa, a stint in Hong Kong, and a job as a jewellery salesman.

By 1977 his dream was to become a racing driver and he set up Mark Thatcher Racing. The operation was soon in the pits with cash problems but Mr Thatcher's determination to make it in the glamorous world of motor sport was eventually to turn him into a figure of fun for the British media.

Taking part in the 1982 Paris-Dakar rally he became lost in the Sahara desert, prompting his mother to be seen crying in public for the only time in her premiership. He had made no preparation for the event but refused to admit he was at fault. This arrogant streak emerged when the media finally caught up with him. He greeted stunned Fleet Street reporters by imitating Bruce Forsyth's popular catchphrase "nice to see you, to see you nice". His father had come to Algeria to help find him, but Mark refused to shake his hand for a photograph - declining to break the habit of a lifetime. Worse still he declined to thank the Algerian rescue team, leaving his father mortified.

His relationship with the press has always been difficult. When he was approached by Mark Hollingsworth, co-author of Thatcher's Gold: Life and Times of Mark Thatcher, he responded by fax: "As you have been informed, I do not wish to speak to you, nor do I have anything to say to you. Goodbye." Tales of his arrogance are legion. He once told an air stewardess who asked his name, "if you don't know by now you never will". His critics say he is insecure, paranoid, and neurotic. He is combative too, and has been known to introduce himself at functions as "the charmless Mark".

He was 26 when his mother swept into Downing Street. But he cut an unpopular figure in the corridors of power. Baroness Thatcher idolised him. "Mark could sell snow to the Eskimos, and sand to the Arabs," she once said. But to those that came across him, he was cold and forbidding. To those in charge of the Thatcher public image, he was a liability. He once asked Sir Bernard Ingham, Lady Thatcher's former press secretary, how he could help his mother win the 1987 general election. Mr Ingham replied: "Leave the country."

But worse was to come. Even before the fiasco in the desert, he had arrived in Oman at the same time as his mother, who was on official business there. He was operating an "international consultancy firm", Monteagle Marketing, acting as a facilitator, introducing people he thought could do business together.

According to Mr Hollingsworth: "The reality of his personality, like many sons of successful people, is that he was desperate to please but did not have the appropriate skills or work ethic to achieve anything. In desperation to do something to please his mother, he took short cuts. This involved getting in deals using his only asset - his name. This is when all the trouble began." A fervent believer in the free market, he believed it was his right to do business wherever and with whomever he chose.

In Oman he is alleged to have helped secure a multi-million deal for Cementation to build a university there. When the story broke in 1984, Lady Thatcher's closest allies warned he must be sent away. He moved to Texas where he met and married the millionaire Diane Burgdorf. In 1986, it is alleged he played a key role in brokering a deal between British Aerospace and the Saudi government, which earned him a commission in the region of £12m. Although the exact figure has never been confirmed, the money from this deal formed the bedrock of his personal fortune. The sale was part of the massive al-Yamamah arms deal, signed by Lady Thatcher. When his involvement emerged, nearly five years later, after his mother's exit from Downing Street, there was an outcry. Senior Thatcherites later admitted that if it had emerged during her premiership, she could have been forced to resign.

Trouble seemed to cling to Mr Thatcher wherever he went. Now a self-styled international businessman, wealthy and well-connected, he continued to court controversy. The security alarm company of which he was a director, Emergency Networks, went bust. Then there was a US Internal Revenue Service investigation into unpaid taxes. He also became embroiled in legal action over his takeover of the aviation fuels company, Ameristar.

In 1995, amid claims that his relationship was in trouble, he moved to South Africa. But still the allegations came. In 1995, it was claimed he used a hand-written note from his mother addressed to the ruler of Abu Dhabi to secure a business deal. His name was even mentioned in connection with the Pergau dam affair, in which British aid to Malaysia was allegedly linked to a £1.3bn contract.

Three years after he arrived in Cape Town there was yet more trouble. He was forced to answer questions during an anti-corruption investigation after his company Matrix Capital was found to have made 900 small loans to government officials. He claimed that he was merely trying to help.

But no wrongdoing has ever been proved. Since then he has kept his head down and last year he inherited his father's baronetcy. But this veneer of establishment acceptance has failed to undo the deep hostility he has generated over the years. The question is: will he escape the latest challenge to his reputation and return to the good life in the Cape?