Moscow, 1994, a week before several of Russia's largest privatisations are due to launch. Jim Mellon is in a covered vegetable market with $2 million in cash in a suitcase. He and his colleagues are snapping up thousands of share “vouchers”, each with a face value of $25, from local traders, concentrating their buying on any company with oil and gas in its name.

The process moves quickly: they are buying from an ill-informed population that has been allocated the vouchers as part of a bumper state sell-off that many of them neither understand nor care about.

“Six weeks later, I was in my house in Ibiza,” the now-legendary investor says as he recounts the story from the relative safety of a coffee bar in West London. “In those days, the house had no phone; there was no e-mail and I had to walk to the local village to collect a fax. My business partner sent me a message to say the privatisations had been a success: That $2 million is now worth $17 million, what shall we do?'

“I wrote back: Sell, of course, and let's set up a Russian fund management company.' So we did. For a while we were the biggest in Russia.”

Mr Mellon, 51, is full of stories such as this. He describes himself as an “opportunistic investor”, spotting the potential of investment ideas, moving quickly to capitalise on them and, in many cases, walking away with a tidy profit.

Mr Mellon's name rarely draws a blank in the City. He is viewed equally as an adventurous entrepreneur and something of a buccaneer. This poses few concerns. He says that he is a “create and hold” rather than “buy and hold” fund manager and he has pledged to give all his wealth away.

He has strident opinions. The Government's tax crackdown on non-domiciled foreigners is crazy, he says, although he is not a non-dom. There is no such thing as a unique investment idea any more: “We are all plagiarists.” House prices in the United States could tumble by between 20 per cent and 25 per cent and it will be years before the credit crisis sparked by the downturn in the American sub-prime mortgage market works itself out. House prices in the UK will fall by 20 per cent in nominal terms over the coming months.

He says that he predicted the credit crunch and its timing almost exactly two years ago. “The US is slightly different to the UK in that it has a potentially unlimited supply. Outside Los Angeles, there are hundreds, possibly thousands, of unsold homes; they don't have the land constraints in America. We saw that bankers, largely investment bankers, in their crazed search for fees, had taken the traditional mortgage debt and cut off the relationship with the borrower.

“At the same time, the banks were very inclined to lend. It felt a little bit like the split capital investment trusts affair, a circle of professionals bankers, builders, mortgage lenders were all invested and all making circular fees. I'm not an economist. It was just common sense that there was going to be an end to the party.

“At the end of 2005, we said that we thought that the trigger for a major recession was the US housing crisis and we said it would come about 18 months later. That's more or less what happened.”

With houses and business interests in Ibiza (still) and on the Isle of Man, Mr Mellon enjoys the trappings of success. He is worth considerably more than he was in the heady days after the Russian privatisations. His entry in the Sunday Times Rich List last year valued him at £620 million, a fortune fuelled in part by the growth of Regent Pacific, the diversified mining group that he set up in 1991 and floated in Hong Kong in 1997.

He still owns a fifth of Regent, alongside his 22 per cent stake in Charlemagne Capital, the emerging markets investment firm that was listed in April 2006, and a crop of other investments. Indeed, an increasingly sprawling financial empire - “I never sell shares in strategic investments” - means that he has between 2,000 and 3,000 staff working for him on projects as diverse as Sleepwell, an Isle of Man-based hotels operation, and Betinternet.com, an online gaming concern.

His business career began in 1979, when, fresh from Oxford University and aged only 21, Mr Mellon was recruited by Richard Thornton, one of two former Foreign & Colonial fund managers who together had founded Griffin Thornton (GT). After six months, Mr Thornton, described as a “difficult but mercurial character who employed only Oxford graduates”, sent his young recruit to San Francisco to set up a new business and manage assets on behalf of American clients.

“This was a fabulous time to be in the US,” Mr Mellon recalls. “The Dow Jones hadn't gone past 1,000 by then. I was very, very lucky to get into fund management, and secondly into an overseas operation.”

Five years later, Mr Mellon became one of a handful of fund managers who left GT to set up Thornton and raise assets to manage in Asia. This was to occupy him in Hong Kong for the next four years, before a sale in 1988 netted Mr Mellon “a couple of million” pounds, after his initial investment of £25,000.

After a short break to enjoy some of his spoils, he established Regent. Sir John Templeton, the billionaire mutual fund investment guru, was his first client and the business formed the basis for a network of private holdings under the banner of Burnbrae.

There is a theme here. Over the years emerging markets, including Russia, China and Asia, have been good to Mr Mellon. But they have not been without their problems.

“We have had two major crises in our history due to emerging markets,” Mr Mellon says, referring to Russia's default on its Eurobonds in 1998 and a row that he had with South Korea's Government over an investment in distressed banking assets about a year later.

“Regent made profits of $100 million in 1997. The next year it lost $50 million. It was touch and go whether we would survive. We did. This is the way it is with the emerging markets. As the chairman of Regent, I have been sued for defamation and threatened with physical violence. Mind you there are no emerging markets left, everything has been discovered.”

Perhaps in acknowledgement, his latest diversion - fully restoring a former Slug & Lettuce pub in Bayswater, London - is unlikely to help him to pay the bills. He couldn't resist buying what is now called The Commander, because it was the place where he met his girlfriend of the past five years.

He is speaking to The Times shortly after a book-signing session to promote his second work, The Top 10 Investments for the Next 10 Years, which has sold 11,000 hardback copies already and offers his insights into most of the big asset classes.

He puts his money where his mouth is, too. He believes so strongly in solar power - it will, he argues, be “bigger than the internet within the next five years” - has driven him to set up his own industrial company, Emerging Metals, which he will be floating on the London Stock Exchange's junior Alternative Investment Market within the next three months. The company specialises in metals used in the next generation of solar panels. “Solar is genuinely clean - it ticks all sorts of zeitgeist boxes. Within five years, solar power will be as cheap as oil and gas without the subsidy.”

Save the environment and make money, it seems a winning combination - one, also, that reflects the man, at least in part. On the one hand, he has a keen interest in staying healthy, in keeping fit, having run 24 marathons. He still jogs with his father, who is 79. On the other, he has a penchant for the odd private jet and for commissioning well known musicians, including 10cc, to play at his parties.

Whatever the investment community may think about Jim Mellon, it is unable to ignore him.

The leader questioned

If you could change one thing in the financial and commercial environment, what would it be?

I would move to a Hong Kong-style tax system, where a flat rate is applied. This would simplify things for everyone and result in increased tax revenues and higher growth. It works

Who is or was your mentor?

Richard Thornton, founder of GT Management

What is the most important event of your working life?

Getting my first job in Hong Kong - it set me on the path as a fund manager

Does money motivate you?

Yes. Both as a scorecard and as a security blanket. But I intend to give all of mine away. If only I knew how long I would live for

What does leadership mean to you?

The respect of others and the ability to marshal complementary talents to common purpose

Which business person do you most admire?

Li Ka-shing. Never puts a foot wrong and makes it all seem so simple

What gadget must you have?

The latest iPod. It is the greatest thing ever invented

How do you relax?

Running and reading - not at the same time

C.V.

Born: February 16, 1957

Education: Ampleforth; Oriel College, Oxford (MA in Philosophy, Politics and Economics)

Career: Joined GT Asset Management in 1979 and worked as an investor in the United States and Asia before setting up Regent Pacific in 1991. Diverse interests stretch from mining in China to the Sleepwell chain of hotels founded on the Isle of Man

Other interests include: Running, Jack Russell terriers, film, reading, writing. Is co-author, with Al Chalabi, of Wake Up! Survive And Prosper in The Coming Economic Turmoil and The Top 10 Investments for the Next 10 Years

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