My jaw hit the floor when, a couple of weeks ago, I walked into a pub to meet my friend Sam and found her dressed as a tramp. Not the vagabond kind, but the Bettie Page kind — which was even more shocking. Sam is a stylist, so she normally wears what I will kindly describe as avant-garde hessian sacks. Instead, much to the delight of some men drooling by the bar, she was sporting spray-on jeans, a low-cut ribbed vest, killer heels and a cropped leather biker jacket with fetish-looking zips. She had accessorised with a glass of ropey house white, an unlit fag and immaculate red lipstick.

Had Hallowe’en come early, I wondered, mindful that — according to the film Mean Girls, at least — it’s the one night of the year when a good girl can dress like a vamp and not be thought a total prosser? But no. Tuning into The X Factor the following evening to see Cheryl Cole launch her new single, what did I find? The Geordie songstress had transformed herself from an Hervé Léger-wearing, Blair Waldorf-channelling Wasp wannabe into a lascivious sex bomb. A pocket square of sheer gauze and some peek-a-boo harem pants were all that stood between her naughty bits and 13m viewers. And there was that red lippie again.

It confirmed what I’d suspected for a while: the sex bomb is back. In Paris, an exhibition to mark Brigitte Bardot’s 75th birthday is drawing thousands of visitors to Boulogne-Billancourt. Meanwhile, Megan Fox, the potty-mouthed star of Transformers, has been drafted in to replace the (let’s face it) fundamentally unsexy Victoria Beckham for the next bout of adverts for Armani underwear. Elsewhere in fashion, the Dutch model Lara Stone is flavour of the month. Stone reeks of sex (in a good way), is practically a Bardot mark II, with curves and a kinky gap between her front teeth. Tellingly, she looks not dissimilar to Georgia May Jagger, the daughter of Mick and Jerry Hall, who, at 17, proved morally problematic sex-bomb material in her outré adverts for the denim label Hudson. The jeans in question were apparently so overwhelmed by her topless sexual charisma, they spontaneously popped open at the waist.

The list goes on: Eva Mendes’s traffic-stopping turn with Jamie Dornan in their billboard ads for Calvin Klein undies (honestly, they’re as lithe and slippery as sea otters) and, last week, the fashion label Guess, which has been using Fellini-esque bombshells in its campaigns for aeons, opened an exhibition of its greatest tits (sorry, hits) in London. Paul Marciano, the smoothie head of the company, explained their appeal to me. “The iconic movie stars of the 1950s and 1960s, such as Brigitte Bardot in And God Created Woman, Anita Ekberg in La Dolce Vita and Marilyn Monroe in Some Like It Hot, or the supermodels of the 1990s, will always represent the ideal of beauty for women,” he said. So why have we been plied with a steady stream of malnourished peasant girls? “Because, in the past few years, the fashion industry has propagated an ideal of beauty that wasn’t feminine, sexy or appealing,” he says with a snort. “People want to dream and to look up to iconic beauties, real women with star quality.”

He’s missed the fun factor. Sex bombs seem to be having more of a blast than waifs right now — and who doesn’t fancy a bit of that? Take Fox, the 23-year-old star of the new thriller Jennifer’s Body. She talks a good game. “I’m just really confident sexually,” she said breathlessly in a recent interview. “I think that sort of oozes out of my pores. It’s just there. It’s something I don’t have to turn on.”

Interestingly, while the sex-bomb look obviously fulfils most male fantasies (dur), it isn’t entirely about appealing to the chaps. This isn’t the case of Eva Herzigova’s “Hello Boys” Wonderbra ads, which worked on the principle that if men thought she looked hot, then women would buy her bra to please them. The Noughties bombshell mostly crops up on the fashion pages of Style and Vogue. Men aren’t even privy to their wondrous curves and smouldering gazes. It’s a girl thing. So why do women want to be so slaggy all of a sudden?

“There is a point when dressing for men doesn’t work,” says Sam, 28, back in the pub. “Your average man just wants you to wear something cutesy, and I didn’t like that, so I grew up wanting to be grungy and like Kate Moss. Now I want to be a Robert Palmer girl,” she says, scraping back her hair for effect. Ironically, it’s done wonders for her in the getting-chatted-up stakes. “You have to be a woman, not a girl, to pull it off. That’s what makes it so great. Plus we’re bored with trying to be tiny all the time. All the best girls in the [Fashion Week] shows this season had a bit of a boob, a bit of a waist. I’d rather look sexier, like I’m having fun.”

Apprentice sex bombs, take heed, though. “The sex bomb’s style is sexy and simple,” insists Marciano. “That’s what makes it timeless and so interesting to the public. If we look at pictures of Bardot from the 1960s, or one of Claudia Schiffer taken in the 1990s, their beauty is still relevant today.” The point he’s driving at is that one must not confuse slaggy with sexy. One must appreciate the obvious line between the amateur stripper look beloved of FHM readers (poker-straight hair, lip liner) and the tousled goddesses of yore. In fact, the rules for sex bombs are strangely unchanged since Bardot first padded along the seashore in St Tropez. It’s about pouty lips, long legs, nostalgia and flirting.

And be careful not to get so smoking that you alienate the sisterhood, as Fox found out to her cost. “I come across as confident and [women] assume that means that I think I’m hot shit,” she said, uncharmingly, of the reason her female fans are few. “That makes them feel bad about themselves and so they hate me.”

Tut, tut. Bad sex bomb.

The sauciest minxes

Lara Stone The curvy model du jour in modern Bardot mode for Prada SS10.

Georgia May Jagger Mick and Jerry’s 17-year-old daughter oozes sex appeal in the risqué Hudson ad campaign.

Raquel Welch An iconic turn in One Million Years BC in 1966 established her as a tousle-haired temptress.

Brigitte Bardot The original sex goddess. Need we say more?

Megan Fox Has just pocketed an estimated £1.2m to replace Posh in the new Armani underwear ads.

Claudia Schiffer Smoulders in an early 1990s Guess campaign.

Scarlett Johansson The voluptuous actress sexes it up for Dolce & Gabbana.

Cheryl Cole She morphed from the nation’s sweetheart into a saucy military minx for her X Factor performance

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