After the Revolution, thousands of wealthy White Russians fled the Bolsheviks and settled in exile in Paris. Ninety years later, thousands have fled the new authoritarianism in Moscow. This time, however, they have arrived with their riches, often ill-gotten, in London.

Britain has become the home of the new Russian diaspora – many of them oligarchs evading government attempts to claw back their wealth or political opponents seeking shelter from President Putin’s crackdown on dissent.

Their presence and their political activities in London are deeply resented in Moscow. And despite Russia’s huge need for London’s financial expertise and its opening to global markets, the Kremlin’s enemies in London are the biggest stumbling block to any improvement in Britain’s present glacial relations with Russia.

Two men in particular are the focus of the Kremlin’s fury: Boris Berezovsky, now sworn enemy of President Putin, the man he brought to power and now wants overthrown; and Akhmed Zakayev, the Chechen actor and supporter of the separatist rebels who Moscow accuses of masterminding Chechen terrorist attacks. Moscow has levelled criminal charges against both and tried to extradite them; British courts have thrown out the evidence as insufficient or argued that neither would face a fair trial.

Mr Berezovksy’s presence has attracted other Putin opponents, including Andrei Litvinenko, the former KGB officer fatally poisoned in 2006, and Badri Patarkatsishvili.

The exiles – Russian, Georgian and Chechen – have brought their feuds, plotting and explosive politics with them. The Litvinenko death sent a shockwave throughout the London community, as intended, and almost all prominent exiles have hired private security guards. What has made the scene especially dangerous and unpredictable, however, is the network of links between the exiles, their political opponents at home, a criminal underworld, freelance hitmen and the shadowy world of former and current Russian intelligence agents. All exiles have stories of murder plots; almost all have been contacted by friendly sources to tell them that their lives are in danger.

Many retain huge wealth, and continue operating their business interests. In London, where an estimated 100,000 Russians have bought houses and made their homes, they move among a large circle of friends. Not all are the Kremlin’s enemies: Roman Abramovich is still on reasonable terms with President Putin.

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