FANCY cars zip along the picture-postcard roads surrounding the village of Mougins on the French Riviera, leaving a trail of herby, continental air. It's a downhill walk to the well-hidden houses of the rich and famous, where big fences and phallic fir trees abound. I press a button on a whitewashed wall and a gruff voice crackles over the intercom: "Who ish it?" I'm tempted to say Sean Connery but I know it's really Duncan Bannatyne. The huge gates purr open mechanically. Security camera lenses poke from high hedges along the path to the £4 million villa. A discreet garden gate opens and I am face to face with the man who sold the world. Or parts of the world, mostly in the northeast of England, in the form of care homes, ice cream vans and other businesses. The grass looks painted. An open kitchen leads across a chair-lined patio to an infinity swimming pool with views across Cannes and the Côte d'Azur. Bannatyne's teeth are pearly white, his skin walnut brown. He is wearing pastel shorts, a short-sleeved shirt and a Rolex that is probably not fake. The multi-millionaire is coming to the end of a 45-day stay at the property and his body looks relaxed, although his eyes are a little frenetic.

Today, he says, is like Piccadilly Circus. A pedicurist has arrived to tend to the feet of his wife, Joanne; Bannatyne will have his own sun-hardened heels rubbed soft again in due course, although he doesn't dwell long on this. A friendly man arrives at the villa with a pool alarm, required by French law to alert homeowners if anyone or anything untoward lands in their pool. A hundred euros. "Ridiculush," says Bannatyne, examining the blue cardboard box. If this were the Dragons' Den, the hit BBC show in which Bannatyne stars alongside other serial entrepreneurs, he might respond to a pitch for the contraption with a gruff: "Ah'm out." It's 34C. Later, Bannatyne will bob about in his pool doing sidecrawl and dainty leg exercises. But for now he slips his shades on, sits in one of the patio chairs and has a quick glance at his fingernails. Oh yes, he says, the neighbours are nice and friendly. "We used to go to Andrew Neil's house for dinner just down the road, and tonight we're going to David Coulthard's place in Monte Carlo. Roger Moore didn't make it to our party this year because his wife wasn't well, but he comes occasionally too."

It's not my imagination. Each famous name comes wrapped in a miniature grin, the glint in Bannatyne's eyes visible even through his dark lenses. It's a look that seems to say three things simultaneously: Do you believe me? How mental is that? How lucky am I?

Bannatyne has been mega-rich since the flotation of his elderly care homes business in the early 1990s, but was drawn into the highest social circles relatively recently. The Sunday Times rich list estimates his current wealth at £310 million (small potatoes considering his German neighbour is worth £8 billion from her stake in Continental Tyres). Bannatyne has become a celebrity not for being rich, but for being rich and on television.

When not filming, he does about five hours' work a week by the pool or in his villa office, and then gets back to some serious relaxing. Sounds tough. In his new book, Wake Up And Change Your Life, he argues that we all could, and perhaps should, manoeuvre our way to such stonking riches with a little spit, tears and elbow grease. The book follows on from his 2006 autobiography Anyone Can Do It.

"People often tell me why they can't start their own business and that's why I wrote this book," he says. "They don't realise how easy it is to make money. It's about removing the obstacles." To prove it, the book analyses a number of wealthy entrepreneurs who played the odds and prospered. "They got over their problems and made a fortune," says Bannatyne. "None of us is special - we just went for it." Of course, we all, in our own ways, go for it - even those who are signing on. But should we all be getting bank loans and becoming our own bosses? "It would make Britain a better place," he says. "It would create more jobs and make the whole country a bit wealthier."

Delegation is one of Bannatyne's key skills. Every so often there is a beep from his BlackBerry, his main link to the Bannatyne Group of companies. In line with his five-hour-week work ethic, the new book was penned by the journalist Jo Monroe, who also wrote his autobiography. "It would be crazy not to use a ghost writer," he says. "I don't believe for a second that Donald Trump types his own letters, or Alan Sugar. But it's entirely my story. Jo interviewed me to find the message I wanted to put across and then put it into paragraphs and all that jazz."

He has already made a seven-figure sum from advances and sales of his two titles. Only time will determine whether the books do the same for anyone else. He is currently in talks with his publishers about a third book. Making hay while the sun shines is a deep-rooted Bannatyne instinct, even now that he doesn't need it. He intends to give away 95% of his wealth before he dies, which he hopes will be at least 40 years hence. He has been involved with charities and projects in Romania and Africa since the early 1990s but was inspired to become a philanthropist after talking with fellow Scot Sir Tom Hunter, who intends to donate his £1 billion fortune to good causes within his lifetime.

But why does he want to give it all away? Bannatyne says, quite simply, that he doesn't know what else to do with it. I wonder whether his children (there are six) have any suggestions? "They will be looked after but they won't be megarich," he says. "They won't be driven around in chauffeur-driven Bentleys unless they make the money themselves."

Bannatyne has always made a distinction between giving, and throwing, his money away. While at the helm of Quality Care Homes, he would ask his employees to re-use office paperclips, and once confronted the kitchen staff over the disappearance of a boiled egg. These days, he has access to a private plane, but jets his family back and forth between the north of England and France with low-cost airline easyJet. "My kids don't know what it's like to be poor," he says. "I've got to instil that in them and live with the fact that they don't know what it's like to have that drive. Kids born to rich parents are different to those born to poor parents - there's no doubt about it."

Bannatyne's own upbringing was difficult. He was the oldest of seven children after the death of his sister Helen in the early 1970s. His father, an Orangeman and a former Japanese prisoner-of-war, raised the family on a shoestring in Clydebank. Bannatyne left school with no qualifications, joined the navy as a stoker, and was dishonourably discharged after trying to throw his commanding officer overboard. He spent six months in solitary confinement at Colchester Barracks. He later spent a few days in Glasgow's Barlinnie prison after being charged with breach of the peace and resisting arrest. He left Scotland in his 20s to work in bars and beach jobs on Jersey, where he met his first wife, Gail, the mother of four of his children.

Bannatyne was in his 30s when he bought a dilapidated ice cream van for £450 at auction in Stockton-on-Tees, and started Duncan's Super Ices, which he built into a small fleet of vans, selling the concern on in the mid-1980s for £28,000 in order to fund his first care home for the elderly.

What if the ice cream van business had flopped? "I think I would have been in jail or in a dead-end job," he says. "I'd have been unhappy and put on weight. I'd have got into some trouble fighting."

With this in mind, he has visited Deerbolt Young Offenders Institution in County Durham several times to talk to inmates about his life and offer them tips on starting a business. "They're supposed to be these rough, hard guys but they all love it," he says. Well, nearly all. One inmate claimed that he had already run his own successful business but had lost it. "I asked why he'd lost his company and he said he'd kidnapped somebody," says Bannatyne. "I asked if it was to get some money or because someone was having it off with his wife and he said: A bit of both of those, actually'."

One gets the impression that it is important for Bannatyne not just to be a success but to be seen as a success, particularly in the eyes of his family. The day his father finally admitted he was proud of him was "one of the greatest moments of my life". He took his mother and sister to Buckingham Palace, when he was awarded the OBE for services to business and charity in 2004. His opinion of himself over time has often see-sawed. On first realising he would become a millionaire he had to hold on to a fence to deal with the tremendous rushes of excitement; and yet he felt guilty for taking a salary and dividends of £80,000 a year from his care home empire.

In 2002, working with long-term collaborator Magnus MacFarlane-Barrow of the charity Scottish International Relief, he founded Casa Bannatyne, a hospice for children with HIV/Aids in the Romanian town of Targu Mures. He speaks in his autobiography about Ionna, a young girl at the hospice who would die soon after from drowning. He has lost the necklace she gave him, which he vowed never to take off, but the effect of the experience is still with him. "The doctor told us not to bother building our hospice because the children would be dead before it opened," he remembers. "When the children first came, they would take food and hide it under their beds. It took them about six months to learn that they didn't ever have to do that again."

One night, moved to tears, he found a quiet place to cry and discovered that he was not alone. "I did what you do when you're emotional in that situation - you go and hide," he says. "I realised there was someone there and it was God." The off-hand way he says this makes me wonder if I've misheard. "He was surrounding me, he was in front of me," he says.

In corporeal form?

"No, there was no face and hands and nails and feet but I knew he was there - I knew I was in the presence of God. It was a phenomenal experience. He said to me: Be a new-age Christian'. I thought about it and said: No, I want to continue being selfish and doing my own thing so no, thank you."

And so negotiations with God were concluded. In what way does Bannatyne think he is selfish? "Oh, many ways, many ways," he says wistfully. "I drive an expensive car, have an expensive house ... There are monks giving their whole lives to other people."

Since the encounter, he has tried to be nicer - "turning the other cheek and doing the other Christian things". A kind of cosmic business partnership seems to have unfolded between Bannatyne and God, a gentleman's agreement of give and take. There have been coincidences that Bannatyne doesn't see as coincidences. "It's like a message," he says. "It's hard to explain." At one point, his eight-year-old daughter Emily was so severely affected by juvenile arthritis that Bannatyne had to carry her on to the plane home from France. "I formed the Bannatyne Foundation and a month later she announced that her arthritis had gone," he says. "Things have happened and I think, God Almighty, there must have been an influence to make them happen'."

A divine influence?

"Yeah."

It seems incongruous that the level-headed number cruncher from Dragons' Den should believe in this kind of quid pro quo with his creator, that goods - in the saintliest sense - can be exchanged for services rendered. But then he is a crusading philanthropist. Bannatyne supports the charity Mary's Meals in Malawi, a programme that provides dinners for children in return for their attendance at schools. He is currently involved in another scheme to support Colombian street children. He was asked to become president of the anti-smoking lobby in the UK since fronting a documentary earlier this year investigating the practices of multinational tobacco companies in Africa. "They're drug pushers," he spits. "They're disgusting." His good deeds will be fuelled by further extension of Bannatyne's Health Clubs, his network of 61 membership gyms in the UK.

The idea that his surname be attached to everything he owns serves a dual purpose: he is now a recognisable brand; in turn, he says, he is obliged to provide the quality that people expect of him. He pinched the idea from American businessman Donald Trump, of whom he is a big fan. "He's done so well," he says. "He's faced bankruptcy and defeat a few times but he's just continued going ahead." He has been following Trump's controversial plans to convert the Menie Estate in Aberdeenshire without too much concern for creatures great and small. "Sometimes people who call themselves conservationists destroy the planet by saying land has got to lie there with nothing happening to it, and that all the ants and beasties should continue to live there," he says. "But humans are more important. Playing golf and having houses is a lot more important than having some piece of land with some little things living on it."

In this Bannatyne sounds more like the dragon of TV fame, where he and others like him act as angel investors to people with fledgling businesses. His first appearance in the show followed a brief flirtation with professional acting. Splitting from his partner Joanne in 2002 (the couple got back together and married in 2006) he took an intensive acting course at the New York Film Academy in London, where he made out that he was an average Joe sleeping on a friend's settee to other students. He stopped going for auditions in 2004.

"The last thing I was in was BBC drama Sea Of Souls," he says. It was a brief role but he loved it. "I was killed by my partner who had just robbed a bank," he says. "He shoved the car into the river and drowned me. It was a great scene." But ultimately, acting wasn't worth the bother. "It's hard work," he says. "You go to about 10 auditions and get one job - it's time consuming and soul destroying."

Casting agents would be unlikely to cast him now, given his profile as a dragon. Neither he nor his colleagues on the reality show are paid their normal appearance fees (Bannatyne charges £10,000 upwards for an after-dinner speech) but his involvement with the show has been hugely profitable. "It makes me a lot of money because I've got millions for my books," he says. "That wouldn't have happened otherwise. More people visit my website and go to my hotels, so it does help me financially, apart from the businesses I invest in." He watches the current series with Joanne in Mougins as it airs. For continuity, the dragons wear the same suits for the duration of filming, so that different days can be cut together. Does he like what he sees on the playback? "Obviously I'm a different person out here by the pool with my kids than when I'm doing a business deal," he says. "But it shows me quite accurately as a businessman." A film crew has already been out to France to interview him at home for a new set of programmes about the dragons and the investments they have made on the show. "Without doubt," he says, "I've been the most successful." He cites Igloo Thermal Logistics, a frozen-food delivery company in which he invested £80,000 with fellow dragon Richard Farleigh for a £400,000 return.

Bannatyne will be 60 next year - "I don't want to talk about it" - and intends to continue making money for as long as he is breathing. Starting the Bannatyne Foundation was easy - "you put your shares in the foundation, and then the foundation sells the shares" - and means his name and legacy will continue long after he's gone.

His regrets, by and large, are few. He knows businessmen who have made their fortunes unethically and doesn't envy them. "They look fat and unhappy," he says, "because they're in businesses that they can't enjoy." He talks briefly about a project he is part-funding in Easterhouse, Glasgow - a day centre for young people from disadvantaged backgrounds that he hopes will be ready by next year.

But the pool is reflecting sunlight like haloes and those hard heels are getting itchy. "I don't want to be too specific," he says. "I just want to help out where I can. There's quite a lot to do."