I'M sitting in my car outside the Darlington-based head office of entrepreneur Duncan Bannatyne. I'm early for our interview, wondering what he's going to be like.

I envisage scenario one: He will swivel to face me in his chair, arms folded, all arrogance and Dragon-like nonchalance. He will make me so nervous with his fixed stare that I will blurt out silly questions like "So, how did you get to be so rich?"

Or there's scenario two - he will charm me with his boyish smile, say "Lindsay" a lot and "Mmm, good question" like a seasoned politician. Smooth.

I look around. What kind of a multi-millionaire has his head office in a red-brick former municipal building anyway? Duncan Bannatyne is worth £168m. Where's the atrium? The swanky glass lift?

Inside, I sit in the reception waiting, staring at the dull grey office carpet and the magnolia walls. In the corner is a stainless steel water machine - bland, functional.

In contrast, Mr Bannatyne suddenly appears, in a bright emerald green jumper and jeans.

"Hello," he whispers, nodding his head and smiling in the direction of the photographer and me before striding off with a chap in a pinstripe suit. He seems slighter than I'd imagined, younger looking than his 57 years. I was expecting a swagger. I thought he'd be at least 6ft 3ins tall.

Ten minutes later, he re-emerges, and we follow him up to his office. He takes a seat behind his desk and stretches out. There are photographs of his children everywhere.

His assistant brings in coffee and we begin by talking about his autobiography, Anyone Can Do It, a reference to his phenomenal success in building up his business empire.

Mr Bannatyne grew up in Clydebank, Scotland, one of seven in a working-class family. He inherited his "unswerving determination" from his father, he says, who also told him: "People like us don't start businesses."

Unlike Mr Bannatyne, his brothers and sister always seemed happy with their lot.

Was he aware he was different to them at the time?

"I can't really remember. I just felt I wasn't really happy growing up," he says, adding it was probably because they were poor. "My brothers and sisters just seemed more content."

Although he passed his 11-plus and went to grammar school, given his poor background he felt a misfit there. He joined the Navy afterwards, only to be dishonourably discharged when he pushed his bullying commanding officer overboard after a dare. Following a nine-month spell in an Army detention centre, he found work repairing farm machinery.

It was only when he hit 30, while living a hedonistic life in Jersey, that he decided he wanted to be rich.

There were a number of factors which triggered a change in him, but the death of his sister, Helen, in 1972, possibly from deep vein thrombosis, had a profound effect.

"I was now the eldest and I felt a huge responsibility to take charge," he writes. "In the aftermath of her death, grief sent me off course, but as the months passed, her memory only made me more determined to make something of myself."

Mr Bannatyne began his business empire selling ice-creams but was never happy with just one van or, later, one nursing home for the elderly. He always expanded faster and faster, pushing himself to the limit.

"Why not when I could make 35pc on return of capital?" he says, in his quick-fire Scottish accent.

Over the decades, his tactics paid off. With every move into a new business area - hotel, health club, casino, radio station - he relished the challenge of learning about a new subject. He sold his nursing home business, Quality Care Homes, for £46m in 1996 and children's nursery chain Just Learning for £22m. Bannatyne Fitness is now Britain's largest independent health club company.

But it has never been just about the money and he says he doesn't regret starting earlier.

"If I'd started my business at 16, I would have regretted not spending some time being single and hanging around," he says. "I don't regret one bit of my life. Even the bits I have hated have made me who I am."

And, one suspects, you can either take him or leave him. He is who he is. And the same goes for his plain, head office.

"Ah, but at least it's paid for and it's not rented, which is the difference," he says, smiling. "I don't see any benefit in having a huge office with an atrium."

Many of his staff from his early days are still with him now, and he has rewarded their loyalty with trusted positions at the top of his companies.

He likes to give his managers the freedom to run their departments and make their own mistakes. His delegation skills have also meant he's been able to concentrate on expanding his business - and spend more time with his children.

He has six children aged between four and 23, four to his first wife Gail, and two to fiancée, Joanne McCue, his former director of nursing with Quality Care Homes. He proposed to her in Barbados earlier this year after 13 years together.

The couple will get married on November 11 at a church in Norton, near Stockton.

Pop star Marc Almond will then perform for 200 guests in the warehouse next to his head office.

In the warehouse? Shouldn't he be hiring a castle instead?

He laughs. "At least nobody can come along and say you're disturbing the neighbours. It's all up to Joanne. She knows what she wants."

Mr Banntyne's enormous wealth has also enabled him to give something back. For more than ten years he has funded children's projects in country's such as Romania and Cambodia and latterly in Malawi.

He's always keen to visit the sites and see exactly where his money has gone, and it gives him a sense of achievement to help out. Some of the people he has met have understandably brought him to tears. At one point in his book, he writes about feeling God's presence, but that he wasn't quite ready for him yet.

"I'm just not ready to declare my total allegiance to Christianity. I still suffer from greed, abhorrence, coveting of my neighbour's wife," he says, grinning. "I'll know when I'm ready and at the moment I'm not."

His charity and business work have seen him made an OBE and his profile continues to grow. His regular appearance on television's Dragon's Den, where people pitch business ideas in a bid to get investment from the "dragons", has led to more television work, which he loves. Prior to becoming a dragon, he'd also taken a keen interest in acting.

"It was an achievement because people said 'You can't go into acting' but I got my Equity card. I love it," he says.

But his acting career may have come to an end now he is becoming famous across the country for being Duncan Bannatyne. He's also taking part in another business TV programme on Living TV called Break with the Boss, due to air this month.

Do people run up to him, waving their business cards and trying to pitch ideas all the time?

"No, not really," he says. "But I'll get about ten a day by email. I don't look at them all. I start reading them and sometimes if they're too complicated I bin them."

Does he ever feel sorry for people making their presentations to the dragons?

"One or two," he says. "Once your mind goes blank, that's it. I remember what it was like when I had to present to the City, I found that terrifying, but now I can go and stand in front of 600 people and speak. I think all of them will have learned by it and will do better the next time."

Perhaps they are put off by his, dare I say it, arrogance?

He folds his arms and smiles.

"I don't think anybody who knows me thinks I'm all that arrogant ... well I am a bit. I don't make it easy for them."

He doesn't see any of the other dragons socially except Richard Farleigh because he also has a house in France.

Mr Bannatyne loves his villa in Cannes. He doesn't have too many extravagances - he lives in Wynyard and has another home in London - but his villa is one.

"I'm at my happiest when I'm at the villa, watching the children playing in the pool," he says.

All the dragons are invited to his wedding - except former dragon Rachel Elnaugh, who left the show after the collapse of her company, Red Letter Days. The acrimony between her and the other dragons is well documented.

Mr Bannatyne was due to take part in Only Fools on Horses for Sport Relief but a nasty fall, which left with him with a fractured bone in his left arm, put paid to that. The experience has not put him off doing more reality television programmes though.

How would he describe himself in three words? He pauses, but not for long.

"Driven, restless and ... arrogant," he says.

Perhaps we can end by him telling us something about himself, something not many people know. He looks vaguely amused.

"OK," he says finally. "Joanne says the biggest unknown secret about me is how much I cry at films and things like that and yet I can go to Malawi where there's children dying of Aids and not be upset. I've been known to cry at films like Toy Story 2 when the little orange couldn't get across the road. Have you seen it?"

Can he ever see himself retiring?

"I'll never, ever retire because I enjoy it all so much," he says. "Besides, retirement means giving up."