It was always clear that they were suffering from a collective burst of estate agent's wishful thinking, since most of them really lived in North Kensington or Queen's Park - districts which, while only an energetic walk away, have never had their reputation gilded by a Hollywood movie.

Clearly the hint the young politicos wanted the public to take was that they were edgy urban types, happy to rub shoulders with all comers in the area that, for most of the post-war half-century, symbolised the problems - and the successes - of multicultural London. Before it was colonized by young Tories, Notting Hill had been home to race riots, Rastafarians and bohemians, trustafarians, and media types looking for thrills.

However gentrified today's Notting Hill has become, with its few remaining Afro-Caribbean or Portuguese faces surrounded by sanitized white wealth, shoulder-to-shoulder bankers and wall-to-wall 4x4s and its summer carnival safely theme-parked, most people still think of it as a little exotic and dangerous. The Japanese tourists who prowl Portobello Market, cameras at the ready, are probably imagining crack dealers in doorways and a general whiff of the unexpected about the place.

Being labelled the Notting Hill Set helped new-generation Tories shed their unwanted young-fogey image - stiffs hiding waddly bottoms under kindly tweed jackets - and reinvent themselves to the public at large as actually living in the 21st century and enjoying it.

So what are they trying to escape from now?

The answer almost certainly lies in the forthcoming novel of Rachel Johnson, sister of Boris and a cheerleader for the NHS. She's been paid an advance in the hundreds of thousands of pounds for a gleeful chicklit book called Notting Hell.

Paying a fortune for this seems a good bet for a publisher. It will be the latest of a long series of fictionalised accounts of life in Notting Hill, taking the district's temperature that stretches back to Absolute Beginners, a book and film dealing with the race riots in the Fifties. Nic Roeg's film Performance had Mick Jagger playing a groovy hippy squatting in magic mushroom-infested Powys Square. Martin Amis wrote about Notting Hill in London Fields in the district's next, trendies-living-with-rastas, anything-goes phase.

In a later trustafarian phase, there was the Hugh Grant film which toyed with the idea that he was a trustafarian (though there was already scarcely a non-white face in the genteel area it portrayed).

By then, most of the real script-writing, film-making trustafarians had left, too, squeezed out by the rocketing property prices of the late 1990s that the film helped raise still further and by the incoming waves of bankers, taking with them their wistful memories of buying pot down the All Saint's Road. The question that arises today is; what is there left to write about in a zone that seems anaesthetized by its own popularity, now that the Mangrove has gone and it's all Tom Conran and Rodeo Drive-style shopping on Westbourne Grove?

Due out in August, Rachel Johnson's book describes banker's wife Mimi, whose husband, the divine Ralph, prefers the trout stream in Wiltshire to life in the fast lane of finance. Then there's Clare Sturgis, childless garden designer, and Gideon, her eco-architect husband. The book is being billed by her publisher, Penguin, as a "witty comedy of manners filleting life in Notting Hill, where residents divide into the haves ... and the have-yachts."

Almost certainly not a good message for the voters, this. Anyone who reads this book will soon put two and two together and realise that, whatever the young Tories are up to in Notting Hill these days, it isn't dancing in the street or rolling a joint. The guess I'd hazard is that the canny young Tories have realized that the moment this knowledge seeps out is the moment when it's time to move on, and out. The game's up.

With this book, Notting Hill will lose the last trace of its lovably raffish reputation and become an updated version of desperately strait-laced Chelsea, where an earlier bohemian past was stifled by money. Even the once-dodgy corners of Queen's Park and North Kensington to which the Cameron group is retreating - so that they can add a bedroom while staying close to the Beverley Hills wealth of Kensington Park Road - will soon resemble nothing so much as the deadly respectability of aspiring, bourgeois Fulham.

The game's up, but it's also over.

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