Boris Berezovsky is undoubtedly a happy man this weekend. The Russian exile’s declaration that he plans to overthrow President Vladimir Putin by force has sent the British authorities into a tailspin and enraged the Moscow government. Best of all, he’s back in the headlines. What’s not to like?

The fabulously wealthy oligarch has not had such fun since he was a king-maker at the court of Boris Yeltsin, only to discover that he had backed the wrong horse in bankrolling Putin as the old lush’s successor. Fleeing to Britain in 2000, he has been trying to bring down his former protégé ever since.

“He’s a charming Machiavellian character whose drug is political intrigue,” said a journalist who has met him several times. “He gives the impression he would stop at nothing, but he can’t accept he’s not a player any longer.”

Still, the 61-year-old former car dealer evidently felt he had gone a bit far by threatening the violent overthrow of the Russian regime, after claiming he was already funding a conspiracy by Putin’s colleagues to mount a palace coup. His later statement talked of a “bloodless” revolution, with popular demonstrations.

Despite the political ruckus he has stirred up between Moscow and London, Berezovsky is convinced he can act with relative impunity from his palatial estate in Wentworth, Surrey, where he lives with his latest wife Yelena and his six children from three marriages.

A previous attempt to strip him of his refugee status, triggered by an extradition request from Moscow last year, was overruled by a judge. Russia appears to regard Berezovsky’s return as the quid pro quo for further cooperation in the investigation into the poisoning in London last year of Alexander Litvinenko, the former KGB spy who had warned Berezovsky of a plot against the latter’s life. Berezovsky, in turn, has accused Putin of being behind the murder.

Mind you, the exile’s personal security is a more delicate matter. A decade ago in Moscow his armour-plated Mercedes was blown up, leaving him with severe burns and decapitating his driver. With an estimated fortune of £800m, putting him 68th in The Sunday Times Rich List of 2006, his protection is the best money can buy.

His 172-acre estate, which he bought for £10m from the former DJ Chris Evans in 2004, is guarded by a security team of former French foreign legionnaires and features bulletproof windows, reinforced steel doors, infrared laser monitors and spy cameras.

“I would not be alive without being careful,” he said. “There are people out there who would like to see me dead.” By which he means Putin’s men.

It’s a hard life: he wakes at 7am, then spends 30 minutes on the treadmill followed by 20 minutes in his private pool. After a breakfast of plain porridge, his Mercedes wafts him to his Mayfair office in London, where he plots Putin’s downfall. He is fond of lunching on white truffles with pasta, accompanied by a glass of Ornellia 95, his favourite Italian red wine. He returns home at 9pm, and after writing political diaries, goes to bed at 3am.

It’s the regime of a hyperactive personality who has been described as a cross between Mephistopheles and Lenin. “He’s absolutely manic and talks at 150mph,” said one visitor. “He’s suave, engaging and has a brilliant mind — but always seems to get it wrong.”

One of his most spectacular misjudgments was fielding the mild-mannered Ivan Rybkin for the Russian presidency against Putin in 2004. Rybkin became a laughing stock when he disappeared for days and then pulled out of the electoral race altogether.

But the mischievous exile pulls off the odd publicity coup, such as enlisting Neil Bush, younger brother of the US president, into joining him on a visit to Latvia in 2005, which left Russia gratifyingly apoplectic. Berezovsky, an investor in Bush’s educational software corporation, was seen giggling in the background as the hapless Bush faced the cameras.

Not surprisingly, Berezovsky loves Britain. “What I most appreciated was that they didn’t play political games, not with me, and especially not with my family.” Nevertheless, he pines to return to his homeland — although not, he has insisted, to take up the presidency himself: “Why would a rich man want a job in politics?” Moscow would dearly like him to return — and go straight to jail. When he left Russia there was a Kremlin investigation into his businesses, resulting in charges of massive fraud and embezzlement from the airline Aeroflot, which he controlled. “If I were guilty, then why should the British government grant me asylum?” he demanded. “The charges are lies.”

He was born in Moscow on January 23, 1946 to a Jewish family of intellectuals and appeared destined for an academic career. After attending the city’s best schools he entered Moscow’s first institute of computer science and he became a mathematician for the next 25 years.

His transition to entrepreneur was accidental. “In 1989 they stopped paying my salary, so I started in business,” he said. “Every Russian had two wishes, for an apartment and a car. The women generally had the last say on the apartment, so I went into cars.”

With the pooled savings of three friends he went to West Germany and returned with a used Mercedes that he sold for three times the outlay. On the next trip he returned with four cars. With a proper system in place, the money grew: “We made our first million roubles, then our first million dollars.” He set up the first Mercedes dealership in the Soviet Union, then negotiated its first chain of car dealerships. “Really, we created the country’s car market. There was no market then.”

Berezovsky was also designing software for the car business and for the new consumer class. Dubbed Russia’s first billionaire, he subsequently inspired a Russian feature film, Oligarch.

He had entered territory occupied by the mafia gangs that thrived under perestroika. In 1995 he was one of the seven oligarchs rewarded for political support of Yeltsin with a series of privatisation deals in which the state’s crown jewels were sold off for a fraction of their value. Berezovsky acquired Sibneft, a newly created oil company, for a cool $100m (£50m). It was later valued at $1 billion.

Thanks to his friendship with Yeltsin’s powerful daughter Tatyana Dyachenko, he was welcomed into the ruling clan and soon gained the nickname Rasputin. A journalist recalled a visit to his Moscow office, a prerevolutionary mansion restored to splendour: “It was like a mini-Kremlin. In a huge salon, senior people from the world of politics and business were waiting for an audience with Berezovsky. Then all sorts of oligarchs would arrive for dinner. He had fingers in every pie.”

Yeltsin was reelected in 1996, thanks in part to Berezovsky’s purchase of the loss-making ORT television channel. By sacking 5,000 of its 7,000 employees, he made it solvent and a mouthpiece for Yeltsin. As his empire extended from television to newspapers, he was a man who could make or break governments.

After 1998 he began planning to install a successor to Yeltsin, and when the little-known Putin was appointed “caretaker” prime minister the following year, he funded the new party that formed Putin’s parliamentary base. Believing the bonanza would continue unabated, he was sorely disabused when Putin turned on the oligarchs and warned them to stop dabbling in politics or suffer the consequences.

Berezovsky disobeyed. “I supported Putin at the outset, but then his centralising intentions became clear and I went into opposition,” he said. He founded a party, Liberal Russia, whose two leaders were subsequently killed. His efforts at peace-broking in Chechnya aroused public suspicion that he was allied with Russia’s enemies.

Accused of plundering the country and hounded on fraud charges, Berezovsky sold up and left the country. He was in London in 2001 when Moscow issued an extradition warrant against him. “I had no choice. I could not go back.”

He claims he has spent millions of pounds supporting activists fighting for civil liberties in Russia, unconcerned about their widely disparate aims.

But can Berezovsky really overthrow his old adversary? Few Moscow commentators would credit it. “The truth is that Putin is highly popular and Berezovsky is loathed,” said one. “He’s often blamed unfairly, but people see his hand in everything that goes wrong. And there is no opposition with any chance of taking on the Kremlin’s candidate.”

The exile is said to be haunted by his last conversation with Putin. With a cold stare, the president told him: “You were one of those who asked me to be president. So how can you complain?”