David Furnish is wearing the most unbelievable diamond ring - 40 exquisite stones lying side by side, encased in platinum and sparkling like the sequins on an Elton jacket.
"This was my 40th birthday present," he says, removing the ring to reveal the engraving inside from Elton.
"You don't get more romantic than that," David adds, quite unnecessarily since it's perfectly obvious, after nine years together, that this is still a hearts-and-roses union. The devoted couple send romantic cards to one another every week and sneak off for intimate breaks . During his recent exhausting world tour Elton would occasionally jet home overnight to be with his lover.
"I do feel very lucky," says David, "but it never occurred to me that we wouldn't last. I never once thought, when we met, 'I'll give this a try'. It always felt like a commitment. I felt strongly that I'd spend the rest of my life with Elton. It was a case of, 'Let's make this work'."
With five homes and massive wealth to share, they've been sorely tempted, he reveals, to adopt children.
"We've both been to Africa on fund-raising projects for Elton's Aids Foundation and we both recognised how wonderful it would be to give one of the children a home.
"We've talked and talked about it but, for a whole bunch of reasons, decided it wouldn't be the fair or right thing to do.
"First and foremost we genuinely believe that a child needs two parents which with Elton's travelling would be a problem. We've seen families who hire legions of nannies, a governess and carers so the responsibility is
"That, most definitely, wouldn't be our choice. We both understand how important it is to invest in your child's life. You only get out of it what you put in. Realistically, too, it could have created tensions in our own relationship, with me at home with kids nagging him because he's not around. That wouldn't help anyone.
"We just had to be sensible about it. Elton's 56 now, which would mean being a father to teenagers in his 70s. You've really got to consider all those things when you're looking at involving a child who will be wholly dependent on you.
"We've been over it time and again and I confess, when you see an orphan child in Africa the temptation is there to bring them back. But we do the best we can in terms of financial support and raising money."
Which is why we're talking in the London shop where, once every two years, Elton sells the contents of his closet for charity.
Once again it's a glittering Aladdin's cave for fans and fashion victims, with designer cast-offs worth £2 million - many hardly worn - stacked on rails and waiting in the basement. Tomorrow more stock will arrive from Elton and David's wardrobes, including designer belts from £50 and swimwear from £30.
Victoria Beckham has donated two dresses and her husband has given a grey Versace suit. The last sale raised £440,000 for The Elton John Aids Foundation and this year the signs are good. The feathered outfit Elton wore in 1977 for a duet with Miss Piggy already has a reserve price of £35,000.
"In 2000," says David, "we shut up shop after six days, when virtually every piece went. We'll do the same this time, just keep going till it's all gone.
"Having a clearout of our things every couple of years is therapeutic and it's a win-win situation. People get to wear and enjoy these lovely clothes and we raise money for the foundation."
It also gives us mortals a glimpse into the kind of lifestyle that can afford to cast off handmade suede Versace coats, beautifully crafted Italian shoes, divinely soft Gucci leather jackets and pile upon pile of Gaultier trousers.
"You've got to remember we're given a lot," says David, "and we receive discounts. I'd be lying if I said we don't enjoy fashion."
Given Elton's legendary shopping habit it's probably fair to say there'll be enough to supply another sale in 2004. "Elton does have a huge appetite for life," says David. "Everything he does is big. He has this enormous drive which is inspirational to me.
"If he'd been an author, accountant - whatever - he'd have been the best. We both have a strong work ethic. I put myself through university back home in Toronto, waiting on tables to get a degree. Now, Elton does his work, I do my film-making. It's vital for our relationship that we maintain our identities.
"Obviously work keeps us apart, but you can only live that life when there's an enormous amount of trust. We are never out of touch and always know where each other are. As long as you recognise each is making the effort to communicate you're OK.
"The only thing we argue about - apart from me eating Twiglets in bed - is how hard he pushes himself.
"Sometimes I'd like him to slow down. I worry about him living life at full tilt. But at the same time I've got the wisdom to recognise I'm never going to change Elton.
"Occasionally it's frustrating having to live with Elton John 'the business'. It's all-consuming and inevitably crashes into your personal life, but that's his career. You can't turn it on and off. "There are times when I just want to spend time alone with him and I'll grumble a bit, but we always make up for it by taking a weekend just for us - no guests, no work, just the pair of us sitting at home watching DVDs.
"Our homes are really our sanctuary. We can't, like other people, just go for a coffee in town, window shop or stroll around. So what we do, when we're being sociable - which we are a lot of the time - is bring people into our home.
You try to create a world within a world, but the challenge is not to cut yourself off, or lose touch with reality."
With celebrities such as Posh and Becks popping in and out that can't be easy. Yet David remains remarkably grounded and approachable. He's warm and friendly, doesn't forget names, shows an interest in other people and seems genuinely unfazed by the lifestyle he was catapulted into when he moved in with Britain's most famous musician.
On the day we meet, Christmas trees are being erected, bunting strung up and clothes sorted for the sale but amidst the mayhem he's an oasis of calm.
"I really try," he says, "to remember where I came from. One of the guests at the 40th birthday party Elton threw for me in Venice was my best girlfriend from back home in Canada. I've known her since I was 12. Old friends and family help to keep our feet on the ground.
"And Elton is plugged into what's going on in the world. He reads voraciously and listens a lot. He's not caught in the past, he lives entirely in the present.
"To me one of the greatest terrors now facing the world is that Aids is on the increase, with a whole generation ignoring safe sex warnings.
"People are frighteningly unaware that it's no longer a gay disease. Around the world it's split 50/50 between men and women. It has no boundaries and if we do nothing else, Elton and I will do our best to raise that awareness."
But not before some relaxation. "We plan to take ourselves off for a week at Christmas," says David, "just the two of us to our apartment in Venice. We'll go out for lunch and dinner, lie in and catch up on movies.
"There's no live-in housekeeper there so we'll do perfectly normal things for ourselves, like make breakfast and load the dishwasher."
And what, I ask, does he give the man who has everything, for Christmas? "Wild horses," he smiles, "wouldn't drag that one out of me."