Oleg Deripaska, last man standing

Who is this man Oleg Deripaska, whose hospitality British politicians from left and right seem so eager to enjoy? Like all the oligarchs who made their first pile amid the turmoil of the imploding Soviet economy in the early 1990s, Deripaska (right) has a history far removed from the floating gin palace moored off Corfu where he entertained both Peter Mandelson and George Osborne this summer.

Now top of the Russian rich list, with a fortune estimated at around £18bn, he is a classic example of the new breed of "entrepreneurs" who snapped up formerly state-owned industries at knockdown prices under Boris Yeltsin's privatisation programme.

With his background as a small-time metals broker, Deripaska, then still in his mid-twenties, decided to carve out an empire for himself in the lucrative aluminium trade. In the process, he encountered stiff opposition from some equally ambitious rivals: the result was the so-called 'aluminium wars' in which killers from the Russian mafia were recruited to carry out contract hits on industry executives, politicians, journalists and factory managers.

"That was a time when you made sure to look under your car in case a bomb was there," one veteran of the hostilities recalls. In such circumstances, he adds, "there was a temptation to deal with competitors before they dealt with you."

Although the post-Soviet business world was undoubtedly a dangerous place, nothing matched the intensity of the battle for control of the aluminium sector. Deripaska was most closely associated with the struggle to take over the Sayanogorsk plant in Siberia, aka the 'Wild East'.

According to one insider's account, the conflict became so intense that a grenade launcher was used in an ambush of his car on a lonely mountain road (Deripaska now denies this). But as a Russian source once observed to me, admiringly, when the dust of the aluminium wars finally settled, "Oleg was the last man standing."

By 2000, having bought up the aluminium assets of his good friend Roman Abramovich, Deripaska was probably the major player in the industry worldwide.

Yet for all his wealth and influence - he reportedly made a point of cultivating Vladimir Putin when the former KGB man was on the way up - in 2006 Deripaska experienced the humiliation of having his multi-entry visa to the US revoked by the State Department.

While no reason was cited publicly, the US authorities were believed to have concerns about his alleged links to organised crime and the veracity of statements he made in support of the visa application. Despite lobbying on Deripaska's account by well-placed US associates (and Putin by some accounts), he remains on America's blacklist. There is no such ban on him in London where he owns a £20m house in Belgrave Square - though he chooses to live mainly in Moscow when he's not sailing the Med.

Given that much of the information about the life and times of Oleg Deripaska was known, some are asking whether Mandelson and Osborne (left) took the trouble to check him out before accepting his hospitality.

As for Deripaska, if it is true that he tried to give £50,000 to the Conservative Party in their capacity as favourites at the next general election, it would be a very small price to pay for what Russians call 'blat' - connections to power. ·