Five years ago, Malcolm Glazer decided to write a book about his success. Like any self-made multimillionaire lacking time or literary talent, he searched for a ghost writer. Allen St John, now a columnist for the Wall Street Journal, was among those called to the Hilton on Sixth Avenue in New York to meet the man who, at the age of 76, is now trying to buy Manchester United.

Glazer, recalls St John, had chosen a cramped twin-bed room to conduct these potentially important meetings. The room appeared to have been occupied the previous night by Glazer and his son Bryan, who was also in attendance. If that suggested a frugal, even penny-pinching, nature, Glazer was eager to confirm the impression. The book never materialised and, in truth, the idea was wholly out of character.

Glazer, the son of a poor Lithuanian immigrant, has generally adopted a "never explain" approach to the many controversies he has provoked during his climb to become America's 278th richest person, according to Forbes magazine's 2004 league table. He is worth $1bn (£530m).

He has not given a proper press interview for years, certainly not since he paid $192m for the Tampa Bay Buccaneers American football team in January 1995.

Apart from the occasional trot down the touchline before home games, he has not tried to bask in the glory of the team's triumph two years ago in the Super Bowl. Tampa fans call him the Leprechaun in reference to his small, round frame and gingerish beard.

"He is different from other sports franchise owners in that he is very much a
businessman and he is proud of that," says St John. "At a certain point, many of them are almost embarrassed to talk about how much money they have made, whereas Glazer is completely unapologetic about that. For him, it is not just about sporting victory but also about business victory. He is just as happy to make money on something as win a championship."

That analysis goes to the heart of fans' fears about Glazer's motives. The would-be bidder has spent about £180m acquiring a 28.1% stake in the club without setting foot inside Old Trafford. He did not watch the team play during its American tour last summer. Nor has he made any attempt to woo the fans with a statement about how he would run the club. Nothing has been done to counter the idea that he would increase ticket prices, as he did at Tampa.

The only personal image that Glazer tries to promote is that of a man who has worked hard for his fortune and cares about his family. The Glazer Family
Foundation's website gives only the briefest account of what it calls a "true
American success story", describing how Glazer worked in the family watch-parts business in Rochester, New York, from the age of eight. When his father died in 1943, Glazer, the eldest son, assumed responsibility for the business at 15.

Thereafter, the tale has less charm. Glazer's 60-year business career,
incorporating property, fish, fast food restaurants, local television stations and nursing homes, has been punctuated with minor court cases. Some are bizarre, even by the standards of America's litigation-happy culture. Soon after the Tampa Bay takeover, residents on a trailer park accused Glazer's holding company of illegally charging an extra $5 a month for keeping a pet and $3 for each resident beyond the first two. Glazer eventually dropped the fees, but not before incurring acres of bad publicity and was dubbed the "slumlord".

The strangest of the legal cases is the one involving his mother's estate,
originally worth $1m. Glazer's dispute with four of his older sisters dragged on for more than a decade in the civil courts. "I don't think they were very happy that mother got a new Cadillac every year and they had to use an old car," he told the Baltimore Sun in 1992.

Recurring themes in Glazer's career - ones that echo in the assault on
Manchester United - are his willingness to employ heavy borrowings and efforts to maximise the bargaining power of relatively small investments. Having concentrated on property in his early years, initially buying rented homes in Rochester, he reinvented himself as a corporate raider in the go-go stock markets of the 1980s. In 1988, he bought 10% of Formica Corporation, the work surface company, and threatened to bid for it before selling the stake to a higher bidder. The following year, he employed similar tactics at Harley-Davidson, the motorcycle manufacturer; he built a 6.9% stake, generated some takeover fever and then sold at a profit.

In the 1990s, he made a killing in junk bonds, a feat that will have required high nerve and astute analysis. Junk bonds were regarded as the toxic waste of the financial system after a series of scandals and defaults. Glazer judged that things could not get much worse, and is reckoned to have roughly doubled his $80m investment as economic recovery ensured that not all companies defaulted on their junk bonds.

Glazer's interest in United probably springs from the same instinct: he thinks it's a bargain, even at £800m. You can see his logic: it is probably the world's most famous sporting club, its stadium is always sold out and its brand cannot be copied. That makes it an enticing prospect for Glazer-style financing - mortgage a rock-solid asset up to the hilt in order to crank up the potential returns. Under the takeover proposal for United, Glazer's direct upfront investment would be only a third of the takeover price.

According to his advisers, Glazer also thinks the current United management is guilty of under-exploiting the brand. If you think £45 for a polyester replica shirt is already quite enough, you have not being paying attention to the possibilities. Arsenal will collect £100m for allowing their new stadium to be named after an airline for 15 years. How much could be generated by attaching a sponsor's name to Old Trafford?

Glazer's record as a successful owner of a sports club rests almost entirely on that Super Bowl victory in 2003. To be fair, this achievement should not be
underestimated. Tampa Bay in its pre-Glazer years was a perennial loser.

Unfortunately for those trying to promote Glazer as a genius of sports
management, the Buccaneers have since reverted to their losing ways. The
value of the franchise, though, has roughly trebled under Glazer's ownership,
partly because he was able to secure taxpayers' money for a new stadium.

Glazer bases himself in Palm Beach, Florida, where he has two huge mansions on the oceanfront. He attends the Palm Beach synagogue and contributed to its construction. He and his wife, Linda, have six children - Avram, Kevin, Bryan, Joel, Ed and Darcie - and it is they who are reputed to have encouraged the move into sport. Joel and Avram are fronting the attempt to buy United.

The bad news for hostile United fans is that Glazer's defining characteristic is his bloody-mindedness. He tried to buy four other American sports franchises before getting the Buccaneers. When he was rebuffed by the United board last year, he responded by buying more shares in a stock market raid. Then he voted off three directors, which cost him his City advisers. So he recruited others and came back with a new proposal. He seems to be a man who does not care what people think of him.