Kate Middleton's mates, the Bunga boys

Sitting opposite skyward-facing telescopes and within touching distance of an antique Martini sign in a room called L'Osservatorio, their confession was a tad foreseeable.

Charlie Gilkes, 27, and Duncan Stirling, 30 - the entrepreneurial double act behind some of west London's most popular haunts - tell me they're "obsessed with detail".

But of course they are. After all, this is the pair who make their guests drink out of teacups under American road-signs at "speakeasy" Barts on Sloane Avenue, and have Margaret Thatcher's speeches playing on a loop in the loos of their Eighties-themed nightclub, Maggie's, an "unpolitical" ode to the former Iron Lady herself. Says Gilkes of their compulsion for perfection: "When we were putting Maggie's together, we found a company in Nottingham willing to make us Rubik's Cube tables. But we sent back each and every one because we noticed the space between each plastic square was too small for us to fit in a cloth and clean.It's always the little things that you don't see or think about that matter most in the end."

Gilkes, the son of a consultant dermatologist at the Lister hospital, and Stirling, whose father runs an audio business, meet me inside Bunga Bunga in Battersea, the pair's recently launched and third joint venture.

Its name, made infamous by Italian prime minister Silvio Berlusconi's lascivious parties, is deceiving. For inside the two-storey "Englishman's Italian Bar, Pizzeria and Karaoke", Ruby, Sabine and Aida are not glamorous pneumatic hostesses. They are wood-fired oven pizzas.

Since their midsummer launch - which saw Princesses Beatrice and Eugenie, the Duchess of Cambridge's younger brother James Middleton, Hugh van Cutsem and the stars of Made in Chelsea file in - overwhelming demand has meant that from December they will be open for lunch, and a newly installed "hole in the wall" will mean early birds can collect a Bunga Bunga breakfast cappuccino from January. As London's middle-market restaurants take a double-dip hit, Bunga Bunga is seeing more than 2,500 customers through its doors a week. TV chef Antonio Carluccio and former Chelsea star Gianluca Vialli are regulars.

"Some people think owning a club or a bar is just an easy way to attract girls," says Charlie, who as well as Duncan is in a long-term relationship. "People might say we own three very quirky, silly venues, but at the core of each are extremely sensible business operations."

Charlie, an Old Etonian, and Duncan, an Old Millfieldian, met when they were both asked to work a Wednesday shift before Christmas at the K Bar in Chelsea (now the Valmont). They realised they had been double-booked and decided to work as a team. Charlie, then on his gap year, and Duncan, who was working as a PR account manager at Freud Communications after bad A-level results had deterred him from university, together pulled in an impressive crowd.

The happy accident made them take stock of their joint strengths and they soon set up Jet Set Parties, hosting regular events at Pacha and the Hammersmith Palais. Charlie, who had started his three-year politics degree at Edinburgh University, "planned all lectures in advance" so that he could fly to London every Thursday morning to work alongside London-based Duncan, before flying back to Scotland late on Sundays.

Their first joint business venture was Kitts, a nightclub under the Sloane Square Hotel which opened in 2006 to which the young royals - and a little-known Kate Middleton - would flock. Soon after, business models for Barts, which was to launch in December 2009, and Maggie's, in April 2010, began to take shape.

"Conceptually, we were curtailed with what we could do with Kitts, but it was our first taste of being operators and not just promoters," Charlie says. "For me, this industry encompasses everything I love: food, travel, drink, property. In restaurants, I'm always thinking, 'How would I improve this décor, this service?' So reclaiming the controls after Kitts, you see, was quite important for us."