'My playboy days are over'

Why not? "Because I went a bit wild!" he says. "I just lost it. I was driving like a maniac, it was amazing and I was doing really well. But I went off the rails a bit in my personal life." Does he mean the bubble baths with model Ruth Taylor and his then close friendship with Lady Victoria Hervey?

"I'm not naming names," he says. "I partied. I went over the top. I made mistakes but everyone has made mistakes in their relationships, haven't they? And Heidi is now happily married to Victoria's ex, Seb Bishop."

So, he was a playboy, then? "To be honest, I don't think I was much of a playboy considering how young I was when I came into the game and what was on offer," he says. "I've had three long-term relationships before Karen." His last one was with Brazilian model Simone Abdelnour. Everyone thought she was the one but ... "Simone is lovely," he says, "but it didn't work out.

"I've always wanted to settle down," he continues. "People think I'm this manabout-town but actually I love being at home. I like going out to dinner with friends, and maybe a club, but really I want someone to make a life with. Karen is remarkable. She has an eight-year-old daughter and I see the way she cares for her. She is intelligent, loving, sensual, funny ... everything I have ever wanted. I hope it lasts. But I have been in this game long enough to know the pressure it puts on everyone involved."

I get the feeling, however, that the person who pressurises Coulthard most is himself. He is a stickler for everything. He says he hates unfinished business.

FOR EXAMPLE, when I ask him about the wedding, he tells me he's not sure where it will be held but that he's put some time aside this month to think about it. "By the end of August I will have it all organised," he says. "The place, venue, everything. All the boxes will be ticked."

All the boxes will be ticked? I ask him. It's a wedding, not a business plan! "Yes, but I am a busy man," he says. "I have no time to do endless lists. We shall invite the people who are happy for us and not those who aren't."

Who wouldn't be happy for them? "Oh, all those people who shake their heads and say it won't last." He won't say more.

At the moment, Coulthard is having to put up with some head shaking in his professional life, too. He used to drive for McLaren (1996-2004) but now he's with Red Bull. He hasn't won a Grand Prix for three years. Rumours of retirement dog him.

"I am not retiring," he says when I ask him what he'll do when he isn't racing any more. "Why can't people understand this? If I said, 'Yes, I'm going to do x after I retire', then it mentally puts me in that place. I have to want to win. I do want to win. OK, I haven't won in a while but I will win again and I'm happy here at Red Bull and they are happy with me."

But why isn't he winning? Is it his age or the car? "Michael Schumacher is older than me and he is still winning," protests Coulthard. "Actually, I think Michael's an actor. He's won so much in his career, yet every time he goes up to the rostrum

he's leaping about and smiling. What's that about? I've never been able to do that. I'm a miserable bleeder."

But maybe he isn't very happy, I suggest. Maybe all those riches and that fame haven't done the trick. "It's true that money doesn't make you happy," he says. "I look at my brother. He lives next door to my mother and father in Twynholm in Kirkcudbrightshire. He runs my father's haulage firm. He is married with children and he is happy. I can see that. He doesn't envy my lifestyle because he wants what he has.

"Now, if I hadn't become a racing driver, I would have done that, too."

Would he have been happier doing that? "I don't know," he says. "In many ways I think I've had a fantastic life. I've been out with women from all over the world and I used to love the travelling, but I am getting older now and I want to settle down."

He says he gets on very well with Karen's daughter, and, yes, he'd like to have children of his own, but "probably when I retire from motor racing. Michael [ Schumacher] has a wife and kids and they come to see him all the time, but I think it's problematic taking your family everywhere with you. It would be for me."

One manifestation of his desire to settle down is that he now stays in a motor home when he is at the track, rather than checking into hotels.

"I much prefer it," he says. "When I was with McLaren, you had to be so careful about everything because of the sponsors. I had to use a Siemens phone, for example. I was told to look happy because that is what the sponsors wanted. I had to be more in the public eye. Now I get to do what I want as long as I say the drink (Red Bull) isn't crap. So, our team have these motor homes with our own things in them and we're pretty private, and I like that."

DOES HE worry about the stresses F1 puts on his body? "I go every year to a clinic in the States where they check everything out," he says. "I know that I am fit and well and not about to die.

"I persuaded Karen to come with me. She was nervous about it. She said, 'I don't want to know if I'm about to die', but I said she might well want to know because of her little girl, so she came and it was all fine."

But what about the risk of serious injury on the track? "I've been doing this a long time," he says, "and I haven't crashed yet."

Of course, he l ives and breathes motor racing. "My father, Duncan, raced for Scotland," he says. "He encouraged me to do it. The first time I got into a go-kart I was useless but I kept on going and I rose up the ranks. My mother, June, and my father supported me and put a lot of money into my career. You can't do it otherwise."

So, does he feel he has to keep going for his parents' sake? "Not at all," he laughs. "They are semiretired and very happy travelling around the world. My sister has a David Coulthard museum she opens during the summer. We're all very happy."

Coulthard says he has to go. He's off to do a bit of PR for Red Bull and then he's off to the firm's centre in Milton Keynes. Busy, I say to him. "Very busy," he says and off he goes. Another box has been ticked.