Why do I hate her so?

An Audrey Hepburn retrospective at the NFT leads Charlotte O'Sullivan to lament the winsome spell she casts over young starlets

Not long before he died, Billy Wilder observed of Audrey Hepburn that "she started something new, she started something classy". 'Tis true, she did, and therein lies the problem. Might one ask what's so great about being "classy" (a polite word for posh accessory that is, by the by, never used about men)? Might one also ask why we should celebrate the fact that we're still stuck with her today?

What hurts, you see, is not just that her films are deemed worthy of a season at the NFT (though that is painful). It's that, even if one slashed and burned every celluloid strip of Funny Face and Sabrina and Roman Holiday and War and Peace and so on, the spirit of Audrey would still be alive and well. Like the evildoer in The Exorcist, she can assume many forms. And modern-day actresses, for some reason known only to God, seem all too willing to be possessed.

The telltale signs of an Audrey putsch? A nice accent, tiny waist and straight back; plus an extensive wardrobe of non-blousey clothes and the sporting of an extremely short fringe. This look suggests a big, beating heart fit to burst from a pure and fragile body. That is to say, it makes you think of little girls/ little boys/ fawns/ colts/ lambkins. That's where the fringe comes in - so perfect for making one look shorn.

Actresses adept at "doing an Audrey" include Winona Ryder, Audrey Tautou (Amélie) and Gwyneth Paltrow. The last has always been compared to Grace Kelly, but Kelly hints continually at inner steel. Gwyneth, by contrast, wants to please - hence her woeful turn in this year's Plath biopic, Sylvia. After an early attempt at brash volatility, her nerve fails and she takes to wiggling her little hands. And widening her blue eyes (especially when standing beneath light fittings while contemplating suicide). Hacking at our heartstrings with a big stick, she does her mentor proud.

Winona paid homage, too, in the loony-bin drama Girl, Interrupted ("Look at me!" her pale face said, "I'm deep but ever so young; please be gentle and give me an Oscar"). As for Tautou, the star of Jean-Pierre Jeunet's French fairy-tale, her 24/7 winsomeness continues to cause suffering. The huge, brown eyes, the pert nose, the gamine body, the shy grin... Hippies suffer acid flashbacks; it's Amélie flashbacks I dread.

Other actresses assume "child-like" qualities with very different results. Take Judy Holliday (pre-Audrey) and Marilyn Monroe (who was working around the same time). They're credibly, and loveably, innocent - because they're so clearly battling against a world that sees them as knowing and lewd and vulgar. (Samantha Morton is the modern-day equivalent - big-eyed, but also fleshy, messily sexual and capable, quite possibly, of farting on demand.) Such women are genuine victims - of the class (or should that be "classy"?) war - and combine an endearing vulnerability with savvy. If they were to be found reading Wittgenstein, we'd suspect them of concealing a comic-book beneath - or trying to swot up.

Needless to say, Audrey and her spawn have no need of such tricks. They're clearly a superior breed; ready-made queens. They're just looking for a man who appreciates the difference, and we're supposed to clap when they find him.

To be fair, Hepburn did try to escape her own mould. Breakfast at Tiffany's was a kind of victory. Think of it as her Klute. Jane Fonda was 33 when she played Bree Daniels; Hepburn was 32 when she stepped into Holly Golightly's slippery shoes. Both women - praise be - look their age: skinny, a little bit frayed and gorgeous. And both convince as fizzy-sad New York call girls, who find it easier to trust their cat than a "nice" regular guy. Hepburn's film feels altogether more plush and upholstered - but she provides an oddly grim core.

But only a horror film (Wait Until Dark) knew what to do with her after that. Hepburn, wisely, all but retired before things became really awkward, and immersed herself in fund-raising for Unicef. In Hollywood, youth is itself a virtue, and age something of a sin. It's especially hard for ingénues. We'll happily worship them for ever, but only through their old films. And, of course, the bright young things are ready to embody their spirit.

Which brings us back to Satanism... So maybe Audrey herself (sigh) isn't the Anti-Christ. The idea of her, nevertheless, needs exorcising. Some academics have referred to the current wave of Audrey love as post-feminist. Pish! It's anti-feminist, anti-human. Decorous females who insist on playing up their capacity for child-like wonder help to make an already anodyne universe that little bit worse. Both untouchable and non-threatening, they equate to air fresheners: up against such fragrance, how can natural smells not seem nasty? Real life is as guilty as the movies. Charlize Theron won an Oscar for playing a low-down, overweight, scowling serial killer. Collecting her award, though, she was back in Audrey mode: pert and trembling and classy as hell.

Audrey Hepburn's films are being shown at the National Film Theatre, South Bank, London SE1 (020-7928 3232; www.bfi.org.uk) until 24 March to celebrate the 75th anniversary of her birth