When you stand in the queue at H&M on November 8, waiting for the doors to swing open on the latest designer collaboration, keep an eye on the characters inside. If you see a skulking figure among the rails of leopard-print dresses, a man whose tan is the colour of chocolate, whose cigar ash falls in trails behind him as he creeps through the store in disguise, that might just be Roberto Cavalli.

“Do you think there will be lots of people queueing?” I asked him at his home, under the watchful eye of photo after photo of Cavalli-clad Halles, Kates and Victorias, three weeks before the launch. “I really hope so. I so hope so. Ah, it makes me crazy! My first thought was to hide under a hat and dark glasses in the store.”

Cavalli is a designer who expects to turn over £490 million this year, who counts Sharon Stone as one of his best friends, owns a 40-metre yacht and has a contract to dress the Spice Girls for their world tour (at the personal behest of Victoria Beck-ham, a woman he describes as “gorgeous, shy and very polite”). Yet the thought of a customer no-show in a week’s time is enough to inject a huge shot of insecurity into the 66-year-old, for all his 30 years’ experience in the business.

Not that he should really feel insecure. The limited-edition “flash collection” (gone in a flash, he hopes) is like a tasting menu of his most appetising signature designs. There are the animal prints, the fringed leather jackets, the white tuxedos and the jewels – albeit plastic ones this time. If you like all that Cavalli stands for, you’ll love the collection.

“It is a line for the evening,” he says. “It comes out in time for Christmas. It was my idea to create a little red carpet for the young.”

He assures me that his motivation in this particular case is not primarily economic. “I want to dedicate the line to all the young people who rate me, who love me, who consider me their idol – and only for this reason, I swear to you. Because from an economic viewpoint (he lets out a hearty, deep-throated, smoke-filled laugh) there is no advantage.”

Making the young happy is understandable. But when you draw little profit from a worldwide venture, you don’t need the publicity (Posh, Ginger, Scary, Baby and Sporty will provide that in bucketloads) and you also threaten to alienate your existing client base, pleasing the youth of today seems less attractive.

What emerges from Cavalli’s “philosophy” is that he cannot resist the role of fairy godfather: “One dress can change your life. If suddenly you look more sexy, one guy can come close to you. Not a dress from Prada – certainly not – but a dress from Cavalli, yes.”

Then there is the small factor of vanity. “I was a bit sad because I wanted to be in the campaign shots more,” he laughs. “I want to feature lots and then disappear. That’s a little secret of mine.”

As a parting gift, Cavalli gives me an exclusive glimpse at his H&M television advertisement. I say glimpse – what I really mean is that he sits me down in front of his computer and plays me the video. Twice. He likes it a lot. But he has good reason; it is hilarious, and he and I laugh out loud together at the end.

The glamour that we have come to expect from the godfather of sexy is there in abundance: the famous, scantily clad models; the Florentine castle setting (his own home, of course); the opulent yet perennially low-slung clothes. But the star of the two-minute show is not a model, an actress or even John Lennon’s son (although he does feature somewhere in the Bacchanalian throng). The short clip gathers pace, seemingly searching for the real star, who finally appears at the climax, utters the last line and looks imperiously over his fashion acolytes in a pair of dark glasses even though the sun has long since set: “What do you mean I am late for the party? I am the party!”

H&M may be all about the young for Roberto Cavalli, but he is enjoying every minute of the ride.

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