He is a tightwad worth $30bn, he is the third richest man in the world. He is also . . . The sage of Omaha

The unsinkable Warren Buffett is the world's third richest man after the Sultan of Brunei and Bill Gates. He dines with the President. But he

drives his own beat-up car, lives in a house he bought 40 years ago and pays himself a $100,000 salary. He buys companies more often than suits, but has no computer in his office, using instead the extraordinary photographic computer in his brain. He is the only person on the planet who has made a $30bn fortune simply by picking stocks, one after another, almost every one a winner, year after year, trouncing the best brains on Wall Street as shares in his own investment company ascended with magical power from $32 a share to $50,000 a share, yet he has never sold one of them. He is the ultimate tightwad whose principles forbid him giving money to his children or allowing share options to employees or executives and whose one indulgence his corporate jet he named the Indefensible.

He has had a lifelong fear of

death, against which he has hoarded the world. When he speaks, the business world holds its breath and markets quiver.

Scottish investment guru Ian Rushbrook says: ''He is totally and utterly unique. Nobody in investment management has ever come close to making the amount of money that he has and nobody ever will again.''

Tired of trying to ''hunt elephants'' in an overpriced US market, Buffett mischievously revealed a fortnight ago that he was building a stake in a leading British company, prompting instant buying of Cadbury, British Airways, Sainsbury and particularly Marks & Spencer, which may yet feel the Buffett finger on its lately rather worn collar.

At last it was London's turn to sit at the master's feet and hear aphorisms such as ''I don't know what the stock market is going to do and I really don't care'', and ''I don't read economic forecasts'', and ''We have no positions in hi-tech stocks and we won't have''.

As much as any President or Hollywood legend, Americans have needed Buffett, the homespun mid-Westerner who has bought and sold Wall Street and hung it out to dry, as their mentor through the scary evolution of business, investing, and capitalism itself over the past 40 years.

It is a role which Buffett embraced from the start. Son of a Nebraska Congressman, he was obsessed by numbers and dreamed of money. At six on a lakeside holiday he made his first profit, buying six-packs of Coke for 25 cents and selling them individually at five cents each. He was fascinated by stocks and bought his first three when he was 11. A year later he predicted he would be a millionaire before 30, explaining: ''It's not that I want money. It's the fun of making money and watching it grow.''

By 13 he was selling lost golf balls, making serious money from a paper round, and filling in his own tax return. At high school he bought used pinball machines and rented them to barbershops, soon making $50 a week. Leaving school, the future ''sage of Omaha'' was already seen as having oracular knowledge of the world - and he knew he was going to live his life in Omaha. At 18 he was running three mini-businesses, had read 100 business books, and decided that one of the country's top business schools had nothing to teach him. He was right.

At student parties ''while most of the guys had their arms around a date Warren would sit on the couch and entertain the party with a little dissertation on the gold standard'', according to Roger Lowenstein's biography. Already, he demystified the financial jungle and made people laugh, combining a Garbo-like lonely mystique with the virtues of preacher and showman.

At 20 he had memorised every balance sheet on the New York Stock Exchange and had amassed $10,000 entirely from his enterprises, recording every dollar in a pencilled ledger. He became a student, then an employee, and soon the leading follower of pioneer Ben Graham, who after the Depression had invented ''value investing'': ignore the herd instinct of the market, find out a company's intrinsic value, buy it when the market is selling it cheap, and hang onto it because the market price will eventually catch up with the value. In short, buy a dollar for 50 cents.

Buffett was enraptured - could Union Street Railway really have assets worth $120 a share and a market price of $45 a share? In those days, it could. By 1956 his $10,000 was $140,000, and from his bedroom he started a partnership managing $300,000 for relatives and friends.

After five years the Buffett Partnership was 250% ahead against Wall Street's 75%, and Buffett at 30 was indeed a millionaire. The first hugely unorthodox bets began. In 1961 he sank $1m, a fifth of the partnership's money, into a dying Nebraska windmill and farm implement manufacturer. It gave back $2.3m in profit. In 1963 when everybody else was selling American Express, he bought it and followed that with 5% of Disney. Amex's franchise and Disney's film library, now cliches, had been unvalued.

When the market soared, for three years Buffett kept his hands in his pockets then liquidated the partnership, having returned 1200% over 12 years against Wall Street's 120%.

He ploughed his fortune, still more improbably, into Berkshire Hathaway, an ailing New England textiles dinosaur which embodied the work ethic Buffett admired.

He began to dispense an annual 7500-word treatise to its shareholders which came to be regarded as a holy grail, and emerged into a new life as a company boss, supremely able to motivate managers and find like-minded business partners - like the untameable 90-year-old matriarch of an Omaha furnishing empire who ended up eating out of his hand.

Rushbrook says: ''He has a quality of judgment that is phenomenal,

coupled with immense personality which enabled him to get close to people in the companies he wanted to invest in.''

Within a year Berkshire Hathaway was making $45,000 from textiles but $4.6m from investments in banking and insurance, then it started to acquire whole businesses, growing over the next three decades into one of America's top 25 companies.

Buffett became a huge re-insurer and a media baron, owning papers in Omaha and Buffalo, a slice of the Washington Post, and control of the ABC network. But his style, though contrarious, was not that of the swashbuckling entrepreneur. He shunned technology stocks saying he did not understand them. Returns from his key businesses were solid, not sexy, partly because he was loath to reinvest in his companies, content to wait for the next opportunity.

He told his managers: ''I'd rather have a $10m business making 15% than a $100m business making 5%.''

But in the 1980s only size mattered, with Wall Street in the grip of mega-takeovers built on junk money. Buffett, a scathing critic of the new financial engineering, became a ''white knight'' friendly investor, rescuing threatened icons such as Salomon Brothers, and Gillette.

Next he staked a quarter of Berkshire's entire worth on Coca-Cola. Every analyst on Wall Street had spotted its massive world potential but thought it was an over-priced gamble. Only Buffett had the nerve, and the cash, to play. Coca-Cola began to fizz. Berkshire shares jumped 66% to $8000. Pepsi-drinking Buffet was now worth $3.8bn - and switched to Coke.

The sage was now dubbed by Forbes a ''folk hero'', and by the 1990s he had become a confidant of the powerful and glamorous, jetting around the country. Yet a visitor would be told ''come anytime, I don't have a schedule''. Meanwhile there were 50 Buffett-made millionaires in Omaha, and hundreds more around the country.

From the beginning he shrouded his valuable ideas in total secrecy, saying he dare not even talk in bed at night to his wife Susie, in case he was overheard. Susie and their three children saw always a distant man in an upstairs room, intensely abstracted ''in his own solar system'' that was also an emotional fortress. She left him in 1977 to take up the position of close friend, helping to install in her place a local waitress who became his devoted companion in a strange ''ballet a trois'' which baffled and disturbed Omaha society.

For a billionaire, Buffett is radical. He rebelled against his Republican father, snubbed an elite club in Omaha because of its racism, and 25 years ago set up a foundation and provided 50 scholarships for black college students. He does not worship the market as the arbiter of individual worth, believes in far heavier taxes on consumption and inheritance, and has fostered an unmoneyed egalitarian spirit in his home and family. But he is sceptical of philanthropy, and his tight purse strings extend to his foundations. He has promised that over 99% of his wealth will go to charity - but not yet.

The agnostic Buffett's childhood fear of death has, according to his

psyche-watchers, fed his craving for control and continuity. His time-warped determination to hang on, to his past, his relationships, his rigid rational principles, and his money, is his trademark. It is also the quirk of psyche and character that has enabled him to keep his stocks when, all about him, others were selling theirs.

A shareholder recently asked: ''What do you want to be now you are the richest man in the country?'' Buffett smiled: ''The oldest one.''