The boy Mark ... adventurer and would-be playboy
Mark Thatcher remains best known for getting lost in the Sahara desert for six days during a gruelling car race in 1982. When he was found, he addressed the world's media with the words of Bruce Forsyth: "Nice to see you, to see you nice."
The episode seemed to sum up the son of Margaret Thatcher as a rather feckless adventurer and wheelerdealer, a man who styled himself as a playboy, but whose character has been described as snooty, cocky and aloof.
Thatcher, now 50, has been subjected to allegations of conspiracy, money-laundering, usury, common-law fraud, deceptive trade practices, theft and assault. But nothing illegal has been uncovered and he has always denied impropriety.
He gained three O-levels at Harrow and joined a firm of accountants. As his mother became Tory leader and premier, he became a businessman.
"The boy Mark", as his father Denis called him, made millions during the Eighties in an alleged arms deal to the Middle East. He lived in Texas, where he worked as a salesman for the Lotus car company. There he married Diane Burgdorf, daughter of a Texan car millionaire. They have two children.
In America Thatcher created a complex web of companies. He came into contact with wealthy Middle-Eastern businessmen and made millions, it would seem, by acting as a "fixer".
The bulk of his fortune was built up over the next nine years, and was said at one time to be £40 million. But he left Texas after a series of disastrous business ventures and costly legal wranglings.
Even after he had settled in 1996 in a £570,00 mansion in Constantia, Cape Town, Thatcher could not escape embarrassment and controversy.
In 1998 his company was investigated-over claims he had been running a "loan-shark" operation among government officials in South Africa.
Now his arrest over allegations he was involved in a planned coup in Equatorial Guinea seems simply the latest in a line of unsavoury controversies.
Twin sister Carol wrote in her autobiography, describing the time when her brother was lost in the Sahara: "The episode did have one benefit. We could relax a little, for Mark had hung an 'occupied' sign on the family's 'embarrassing relative' slot."
