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When Mourad Mazouz arrived in London 12 years ago, he couldn’t find anywhere to get his couscous fix. France’s thriving North African scene had failed to make it across the Channel. So he started his restaurant, Momo, down an unpromising alley off Regent Street, in what had previously been a dry-cleaners.

You do wonder where the international jet set would hang out if he hadn’t. If you’re looking to keep up with the Joneses – Catherine Zeta, Mick and Tom among them – head for Heddon Street. In 1997, Madonna threw a party for Stella McCartney at Momo before it officially opened, and she has been a regular there ever since. Tom Cruise once rang up wanting to recreate the restaurant for a party he and Nicole Kidman were throwing in the Tasmanian desert, and Angelina and Brad pop in for a bite when they are in town.

Perhaps it is the restaurant’s proximity to Savile Row, but it also draws a high-fashion crowd. At any time, crammed on the sofas in the scented, subterranean depths of the Kemia Bar, Tom Ford, Alexander McQueen, Jasper Conran or McCartney may be found swapping hemline tips with Kate Moss.

It isn’t just the food (raw tuna with aromatic spices, tiny pigeon pastillas and slow-cooked lamb, washed down with killer Momo specials); it’s also the dark corners and dim lighting that make it a haven for publicity-shy celebs. “I sat down next to a woman in the Kemia Bar,” says one regular, “and suddenly realised it was Madonna.”

Meanwhile, paparazzi have been discouraged from loitering outside, and staff are under strict orders never to tip them off. “I would never tell on anyone who eats here,” Mazouz says, looking appalled at the thought. “They come here to eat, and we leave them alone. I need to make it as normal as possible for them.”

Ten years on, Moroccan-inspired cuisine is everywhere, and it sometimes seems that no self-respecting provincial bar is complete without floor cushions and pierced metal lamps. By rights, Momo should have been taken over by the bourgeois crowd, but, somehow, it hasn’t. That must be down to Mazouz, who is effortlessly cool in the way that is possible only if you really couldn’t care less.

Aside from his restaurants and bars (in London, he owns the £12m Sketch, which comprises several restaurants, one with a Michelin star, an art gallery, a tearoom and loos covered in Swarovski crystals, plus the Mo Tearoom and a share in Club Gascon; there are also restaurants in Paris, Ibiza and Dubai), he owns a record label that puts out the music he likes to listen to, and is best friends with Roland Mouret, the DJ Claude Challe and Tracey Emin.

And, even though he is 44 years old and has a toddler son, it’s a rare party animal who can keep up with him. Momo’s 10th-birthday party earlier this month proved no exception. More than 1,000 guests descended on the Heddon Street HQ in the space of 12 hours. First up came countless children, who made face masks in the Momo kids’ club and hung out in the Moroccan-decorated marquee with their kaftan-clad yummy mummies. Then, as the evening drew in, the night owls came out to play – and a beautiful and cool crowd it was, too, including Emin and Mouret, as well as Dan Macmillan, Charlotte Tilbury and Alice Temperley. The restaurant’s former managers came back to help; seven Algerian and Moroccan bands and musicians appeared, including Rachid Taha, a leading light in the world-music scene, who got the crowds dancing on the tables; and the food circulated without pause – as did the host.

It must have cost a fortune, but such considerations didn’t enter into it for Mazouz, who is famously uninterested in the bottom line. “I didn’t want to host a cocktail party,” he says. “That was boring, and I wanted to have fun. Of course, it is a lot of trouble – so why do I do it? Because I like to please people.” A philosophy that other restaurateurs, pondering on the secret of his success, might do well to follow.

Momo, 25 Heddon Street, W1; 020 7434 4040, www.momoresto.com

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