Elton's my bedrock

David Furnish has a gift for intimacy - and this, perhaps, is why he is so widely adored within the celebrity circles in which he moves. When I tell him I have a sore throat - I can't help it, he just looks so sympathetic - he springs straight into action. First, a glass of water, then a sachet of vitamin C.

"One thousand milligrams," he says. The effect is as cosy as being wrapped in a cashmere blanket. For a few seconds, you feel as if no one else in the world matters to him apart from little old nonfamous you.

We meet in the colourful west London offices that house both his production company, Rocket Pictures, and the Elton John Aids Foundation, of which he is a director. He is neat and good-looking, and far more soberly dressed than he ever is when I spot him among the glossy pages of Hello! (not a silk Versace shirt to be seen). He is wearing leather trainers, a brown, long-sleeved T-shirt and - his only visible concession to luxury - a pair of suede Junya Watanabe combats so pale you wonder how he ever dares sit down. "Great, aren't they?" he says, when I admire them.

The Aids Foundation celebrates its 10th birthday this year - and it is also, coincidentally, 10 years since Furnish met and fell in love with Elton John at a dinner party at his house in Windsor (he felt a "twinge" as soon as he clapped eyes on him, for all that he was not much of an Elton fan).

Furnish will happily discuss both these landmarks but Aids, as he makes clear by arriving with a sheaf of fact-strewn papers, is to come first on the agenda.

"Transmission is up 20 per cent in the UK, and it is a vast and growing problem across the rest of the world," he says. "It's important that people realise that, but also that even a small amount of money can transform people's lives."

Not long ago, he went to Africa, where he saw this for himself. "It was incredibly moving. I found it really hard stepping back into my own life. I'm unbelievably blessed."

Over the past decade, the charity has raised $40 million (£23 million), money that is used for both care and education in 55 countries. Furnish shows me a photograph of a course he attended in South Africa, where traditional healers were educated about Aids, and another of home care workers with bicycles - both schemes funded by the Foundation.

Charity fatigue, he tells me, is not a problem where he and Elton are concerned. "We're so passionate about what we do. Our most successful event is the White Tie and Tiara Ball, which we hold at our place in Windsor. Last year, that evening raised £2.1 million alone. The key is: put on a great event and then get to the people who have money. You want people to write cheques. You need to be aggressive about it."

Does Furnish ever wish that the press made more of his charity work? It cannot be easy, always being portrayed as the grinning best friend of Liz Hurley, Victoria Beckham and co. "I don't do it for publicity," he says. "We in the developed world have a responsibility to look after other people. The nature of the business I'm in [film production] is that projects take a long time to get off the ground. So everybody looks at me and says: 'What does he do?'

But my friends and Elton, they know how hard I work." Before he met Elton, David Furnish was a Clapham-dwelling advertising executive. He doesn't miss his old life at all, but he still has "pinch me" moments, even after all these years. "Elton leads an extraordinary life; you never get blase about it."

A year into their relationship, Furnish made a fly-on-the-wall documentary, Tantrums and Tiaras, about his partner. Elton, it must be said, did not come out of this hissy-fit of a film particularly well. Has he changed in the years since?

"Oh yes. He's a lot more content than he was back then. I guess part of the reason is the security that you get from a great relationship." And does he feel the same way? "My relationship with Elton is my bedrock. I go to clubs occasionally with friends, just to have a look at the scene. I get this really sick feeling in the pit of my stomach, real feelings of loneliness, and I go back home and I say: 'God, I'd hate to be single again.'"

So, what's their secret? After all, 10 years is a long time - particularly in their flurry of a world.

"Honesty and communication. When we met, Elton had just come out of treatment and he'd done a lot of work on himself and he knew not to keep things bottled up. I wasn't so good in that area. He helped me to get my thoughts and feelings out openly. There's a lot of laughter that goes on, and we both have the same interests: music, the arts, our dogs [they have 27 - their "babies" - scattered about their homes in Britain, France and America]. There's a rhythm between us. We have an unwritten rule that we try not to spend more than three weeks apart. Break that, and it can be difficult."

Furnish grew up in a small suburb of Toronto. His father was a company director, his mother stayed at home. He didn't really come out as a gay man until he was seeing Elton: he had to tell his family before they got "a knock on the door". They took it in their stride, and he now feels guilty for having underestimated them.

"I was ashamed of my sexuality. I'm 41 now. People forget that even a few years ago there was a lot more discrimination. There weren't any Will and Graces on television. When HIV hit ... God, it was terrifying. I was just on the edge of figuring out who I was. I wanted to get married and provide for children." Is he saddened that he now never will?

"Yes. Elton and I talked about having kids, but it wouldn't be right for us. Elton's always travelling. Sure, we could hire someone to look after the kids, but I don't think that would be fair. So we have adopted children in Africa, and these" - he springs delightedly out of his chair and gestures at the black and white photographs on the wall - "are my godchildren."

Furnish points out little Brooklyn Beckham, Damian Hurley, son of Liz; and Esme, daughter of Susannah "What Not To Wear" Constantine. "David and Victoria have also asked us to be godparents to Romeo," he says.

So what is his view of the rumour that the Beckhams' marriage is on the skids? He sighs. "I spoke to them yesterday. They're fine. It's hard. Take any family, relocate to another country where you don't speak the language and you're living in a hotel, and then on top of that you're being hounded by the paparazzi.

Victoria said: 'David, I can't take the kids outside the hotel. They're climbing the walls.' She can't win. If she sits back, does nothing, everyone says: 'She doesn't do anything.' But if she's away from David working, they say: 'She should be supporting him.' They're absolutely fine. They're in great shape."

I suspect that at least some of his sympathy for Victoria comes from having often been in a similar situation himself.

I ask him what he buys the man who has everything for Christmas. "It's pretty difficult," he admits. This year, however, he has had a genius idea - although, alas, I'm sworn to secrecy. Does he know what he will be getting in return? "No, but I always say that living with Elton is like living with Santa Claus. Show an interest in anything, and it will just appear. So I try to keep quiet."

They will spend the holiday in their "little" apartment in Venice. Who cooks the turkey? "We go out for dinner. That's another thing we have in common - neither of us cooks." He smiles. Elton has already been on the telephone once, and I get the idea that my time is up. I go home to nurse my cold - and David, I guess, goes off to get ready for yet another glammy, "pinch me" evening.

For more information about the work of the Elton John Aids Foundation or to make a donation visit www.ejaf.org