That 'je ne sais quoi': How French actresses trounce everyone in the style stakes

When the French actress Marion Cotillard swiped the Bafta for Best Actress from under the noses of Keira Knightley and Julie Christie, she not only trounced them on the big screen, but also on the red carpet. The star of the Edith Piaf biopic La Vie en Rose, Cotillard looked radiant in short, sequined Chanel, making everyone else seem stuffy, including a rigid, pouting, Dior-clad Knightley.

It was the perfect example of it being not what you wear, but how you wear it. Cotillard may be 10 years older than Knightley, but she embodies the quirky, flirty insouciance that French women do so well, and we Brits rarely seem to get right. Two weeks later, Marion won the Oscar for Best Actress.

This June sees the release of Priceless, a glamorous romantic comedy branded the French Breakfast at Tiffany's. In it, Amélie's Audrey Tautou stalks the Côte d'Azur looking for rich men to keep her in couture. Watching her trade sex for designer trinkets, one can't help thinking that, were the film set in Britain, there would be a whiff of Footballers' Wives about it. But there's nothing trashy about Audrey Tautou. Instead, she conveys the irresistible mix of simplicity and sophistication of that other stylish Audrey, Miss Hepburn.

Vanessa Seward, the creative director of Azzaro, the designer label behind most of the dresses Tautou wears in the film, agrees. "Audrey Tautou has the gamine-like charm of Hepburn," she says. "She can wear very sexy clothes without ever being vulgar."

This is the essence of French style. One of the Azzaro dresses in the film, appropriately called "Tramp" thanks to its indecently plunging neckline, is carried off with a giggle, a wink and not a hint of desperation. As a result, it's more Riviera chic than China White strumpet. "French women are able to wear expensive clothes in a casual way that makes them look cool," explains Seward. "If they wear sophisticated clothes, then the make-up and hair will be light and soft, never overdone."

So, is that our problem? Do we Brits just make too much effort? Not in the case of our female politicians, who were recently branded "Dowdy Street" by the tabloid press, in comparison with their French counterparts. A recent Elysée Palace banquet unleashed the kind of red-carpet glamour generally reserved for the Oscars, with a special mention for the 42-year-old French Justice Minister Rachida Dati in a spectacular floor-length blue gown. Needless to say, our Gallic friends make it all seem frustratingly effortless.

Take the most French of fashion institutions, Chanel. French women don't truss themselves up in the woven-wool skirt suits. Rather, they give the designs a twist that proves the timelessness of the fashion house that's nearing its centenary.

The queen of Chanel is, arguably, Vanessa Paradis, who has been associated with the label since the iconic birdcage campaign of 1992. Even her daughter, eight-year-old Lily-Rose, has her very own pink Chanel handbag. "She is such a girlie girl!" Paradis has remarked by way of explanation. "She was rocking perfectly in my Chanel pumps when she was two."

If Chanel represents sophisticated French style, albeit with a twist, Balenciaga offers a more rock'n'roll, crushingly cool alternative. Leader of the Balenciaga pack is, of course, Charlotte Gainsbourg, daughter of the über-stylish British actress Jane Birkin and French singer Serge Gainsbourg.

Charlotte Gainsbourg has said she will only wear designs by Balenciaga's creative director Nicolas Ghesquière. "I don't pay attention to other things," she once said, "because I just like what he does." Watching her on the big screen (her wardrobe in last year's romantic comedy I Do consisted mainly of Ghesquière's military jackets), it's easy to see why.

But, classic tailoring aside, French girls have a way of wearing clothes that, on any lesser mortal, would look simply ludicrous. Lou Doillon, another of Birkin's offspring, this time with the French director Jacques Doillon, has just launched a capsule collection of denim pieces for Lee Cooper. Her signature piece, a pinstripe tail jacket, styled with a top hat, is described as, "the Artful Dodger, had he fought in the French Revolution". Not a look many of us could carry off.

And style isn't only a young girl's game in France. There's Juliette Binoche, 43, Emmanuelle Béart, 44, Julie Delpy, 38, Sophie Marceau, 41 – all looking better than most of us did at 25. Lou Doillon explains: "They know what suits them. In France, you would never see a fat woman trying to dress like Kate Moss – they know they would look absurd. French girls dress to suit their body."

The French actress Clémence Poésy, who stars in the new Colin Farrell film, In Bruges, has her own theory: "It's important to be yourself. What you wear reflects what you are, so you need to be strong enough on the inside to ignore what the fashion gurus say you should wear on the outside."

So the je ne sais quoi of French style will remain just that, although that won't stop us longing for the self-assurance that underlies the mix of innocent mischief and sophistication expressed through French women's clothes. But, before you enrol on a French course and move to the Left Bank, remember that here in the UK we many style icons of our own.

Take Poésy's fashion inspirations. "Marianne Faithfull, Mick Jagger and Jane Birkin," she sighs,. Yes, all British. And, as cool as Gainsbourg and Doillon are, it's their British mother who has the most iconic of handbags – the Hermès Birkin – named after her. You can't beat that.