The 43-year-old founder of Jimmy Choo at the Four Seasons.

At the beginning of my lunch with Tamara Mellon, the 43-year-old founder and present chief creative officer of Jimmy Choo, the maître d' put us in the wrong room at the Four Seasons. Or, to be fair, he put me in the wrong room. There are two: the Grill Room, which is small and woody and near the bar, and the Pool Room, which is a much grander space in the back, set around a large burbling fountain. Fashion people tend to like the Grill Room; bankers and captains of industry tend to like the Pool Room. Mellon's uncle-in-law, Jay Mellon, for example, the Mellon family patriarch, likes the Pool Room, and that's where he takes her when they have lunch. Which may be why the maître d' assumed she wanted to sit there when we met.

But as anyone who reads both the tabloid and the broadsheet press knows, when it comes to Tamara Mellon, you should never assume anything. So five minutes after I start drinking my Pellegrino in the Pool Room, a rather flustered waiter appears and apologetically takes me back to the Grill Room.

Where I find Mellon, on a banquette, snuggled up under the arm of financier Nat Rothschild, giggling. She is wearing a leopard-print silk sheath dress and towering black Jimmy Choo booties, which look familiar from a YouTube video I had seen of the walk-in closet in her gigantic Fifth Avenue apartment (which she bought from Warner chief executive Edgar Bronfman Jr., as detailed by blogger the Real Estalker, for $20 million), including her hundreds of pairs of Choos.

In other words, she looks just like the sort of trophy wife you might expect to see sitting with an international mover and shaker in a quintessential uptown New York restaurant—except she is neither a wife (she was very publicly divorced from Matthew Mellon in 2003, complete with acrimonious court case and allegations of computer hacking, but they are now friends) nor anyone's trophy. On the contrary, these days she is busy collecting trophies of her own.

Earlier this autumn, for example, Mellon was in London receiving her OBE from the Queen for services to British fashion. Jimmy Choo has 115 stores in 32 countries, and has been valued at close to £500 million. Then, the week before we meet, she was named as one of David Cameron's new global trade envoys, along with fellow accessory supremo Anya Hindmarch and Sir Anthony Bamford of JCB, among others.

"I was surprised," she admits as we take our leave of Rothschild (who has his own lunch guests) and move to our table. Not so much, she continues, because unlike Hindmarch and Sir Anthony, she hasn't been very involved in Conservative party politics (though she did meet George Osborne in 2006 when they sat on a council for British enterprise together) but because of, "Well, who I am."

For instance, I say, because when you Google "Tamara Mellon," one of the first things that comes up is a profile in Interview magazine, published earlier this year, which was accompanied by a Terry Richardson portrait of her naked, lying on a couch with her head thrown back, smoking a cigarette and holding a cat over her nether regions?

"Yes!" she laughs, completely ignoring the menu. "I could not believe the Daily Mail used [the trade envoy appointment] as an occasion to reprint that picture—especially because Terry holds the rights, so I thought I was safe, because he'd never sell it. But they just took it! Now he's made them take it down, and it's off the Interview website, but still."

Did you really not think that would get out, I ask? Could Mellon, who has had numerous newspapers print paparazzi shots of her snatched while (one example) sunbathing topless on holiday with a former boyfriend, Christian Slater, really be that naive?

"It has such a niche audience, Interview," she shrugs. "It's such a specific thing. I really didn't." And despite my obvious incredulity, she opens up her blue eyes and rolls them at herself and insists she really was that uncynical. And I kind of believe her.

Besides, the prime minister and his gang don't appear to mind—at least they haven't said anything to her—and neither did TowerBrook, the private equity company that currently owns Jimmy Choo, when the story was first published. "It went over very well, apparently," laughs Mellon, as though she can't quite believe it herself. After all, normally, if a member of a global company's C-suite were to pose naked, the resulting outcry would involve not only questions of propriety but probably shrieks about questionable judgment and requests to step down. That's what I would think, anyway. But then I—like the maître d'—would be mistaken. Besides—"We should order!" Mellon cries.

It's been 20 minutes since we moved tables, and a waiter is hovering. I thought she just wasn't hungry. "I'd like the tuna carpaccio and the Dover sole," she says, which is a main course more than anticipated (as expected, however, there is no wine involved, only Diet Coke; this is New York, after all, and she's been sober for "about 15 years"). I ask for the tuna, and tack on some soup to keep her company. Mellon may be skinny, but she eats: the day after we meet, which happens to also be Thanksgiving, she is planning to have lunch with the retired couturier Valentino Garavani, followed by Thanksgiving dinner with her ex-husband's family.

She has effectively been absorbed into the Mellon clan; they are one of the reasons she moved from London to New York in 2008: so that her 8-year-old daughter, Araminta, could be closer to her father and his tribe. Although Mellon was close to her own father, Vidal Sassoon co-founder Tommy Yeardye (he was her earliest champion, giving her $150,000 to start Jimmy Choo), she has called her mother, Ann, "a sociopath," and since her father's death in 2004 no longer speaks to her, or her two younger brothers.

Living in New York also helps Mellon to avoid the paparazzi. And the United States is one of Jimmy Choo's biggest markets.

"I knew, from the start, that we needed to be in the U.S. because of the buying power here," she says as the tuna is deposited in front of us. "You can't be global without America, and I always wanted to be global. It normally takes a British brand 20 years to get across the ocean, but we opened three stores in America between our second and third years in business, and we were able to do it because of what we did by coming to the Oscars and having the shoe suite." In what has now become an annual tradition, Mellon famously set up shop in the Peninsula Hotel the week before the academy awards and hand-dyed shoes to match celebrities' gowns, one of the first brands to exploit the power of the red carpet.