French fancy: Cecile Cassel

Cécile, 26, is the only child from Jean-Pierre's second marriage to Anne, a sports agent, and grew up oblivious to the fact that her father was a film star. 'He was my idol but for other reasons,' she says. 'He was another generation [Jean-Pierre was 49 when she was born] so at school he was the hero of all the mothers. I think my problems started when Vincent became a big star with La Haine. I was 14, which was exactly the generation for this movie, so it was more difficult to live with that.'

Her father kept working until two months before he died, in 2007, and was merely amused when, aged 17, Cécile announced that she wanted to be an actress. 'He said, "Oh, finally," ' she remembers. 'I danced from when I was four and then I had singing lessons. I was really in an artistic mood so he knew it would happen. He taught me the pleasure of working hard. He was always working, doing tap or piano or reading a script, and for me that was the big lesson. I know that in England all actors can sing and dance and do everything, but in France that is really original.'

She left school at 17 and started waitressing to pay for drama classes, but it took only a year for her to win her first lead role, in 2002's La Bande du Drugstore, written and directed by French novelist François Armanet. 'People saw the movie and I started getting more offers and castings,' she says, 'but I don't think I was ready for it. It was that typical French movie that shows off the fresh girl, the upcoming girl, but I wasn't ready.'

She battled on with bit parts and drama classes and in 2004 won the part of Chloé Petrovsky, the daughter of Mikhail Baryshnikov's character Aleksandr Petrovksy, Carrie's boyfriend, in the final episode of Sex and the City. 'I had never seen the show, which was good for me because, although I knew it was supercool, I was not frightened at the casting,' she says. 'Then they called me and said, "The good news is that you're in; the bad news is that we have a problem with locations in Paris, so we are going to shoot in New York and we don't know if we can get you a visa in two weeks.'

With 48 hours to spare, the visa was faxed through and Cécile was told to jump on the next plane. 'Sarah Jessica Parker was so relaxed and straightforward, and she spoke in French just for me and did everything to make me feel comfortable. For me, the big thing was meeting Mikhail Baryshnikov. For me he is God. He is the most adorable person and so handsome and beautiful.'

She feels that her big break was Eric Rohmer's tale of love in the time of the Druids, Les Amours d'Astrée et de Céladon, in 2006. 'Something happened with this movie and I was prepared,' she says. 'Eric is really a hero in France and I think that, when he cast me, there was a curiosity. When you are in Eric Rohmer's hands, everyone looks at you in another way.' Soon after that Cécile made a counterintuitive move and decided to move to London for a few months. She had one eye on international cinema and wanted to improve her English, which is now fluent, if accented. 'I lived on Sloane Square - very posh,' she says. 'I wanted to learn the language but I also wanted some fresh air, something new. I really feel like I'm in an old country when I'm in Paris, and in London there is new energy, there is something really refreshing. Even though London has the old City and all that stuff, you feel that it moves quicker than Paris.'

She was sent to a London casting for the lead, Gemma, in a British romcom called My Last Five Girlfriends, loosely based on Alain de Botton's Essays in Love. 'It is really a romantic comedy done in the way that only British people can,' she says. 'It is funny and cynical and romantic. It's about a guy writing a suicide note and talking about each of his last five girlfriends.'

Having fallen in love with the script, she went to audition for the role of Gemma but was deemed too French. However, they called her a couple of weeks later and said that London was a multicultural city and there was no reason why one of the other girlfriends, Rhona, couldn't be a foreigner. 'I almost had a heart attack,' she says. 'It was like a big welcome to me from England.' The film, co-starring Naomie Harris and Brendan Patricks, is due to be released here in late summer.

Now Cécile is back in the Marais about to start the promotional work for Ex, an Italian film. She will then start filming a new film with Benoît Magimel, a popular French film star.

Cécile's life is like a roll call of France's finest. Nevertheless, there is a distinct lack of ennui about her. Her friends, she says, always tell her what they really think. 'And Vincent doesn't say much. When it's good, he doesn't say a word. When it's not good, he has many things to say.' She laughs and says, 'He's a big brother. For my father, though, I was perfect.'

She has an on-going relationship with Louis Vuitton and Chanel and a campaign of some sort will surely be just around the corner. She harnessed even more personal glamour through a three-year relationship with the devastating French pin-up Gaspard Ulliel, star of Hannibal Rising and Kate Moss's Longchamp campaign co-model. They split up last year but remain friends. She has a new boyfriend whom she describes only as 'somebody'. He is not an actor.

She is 'not crazy about the whole LA thing' but hopes to work with Sam Mendes and Baz Luhrmann. And if her English goes from good to perfect, there is no reason at all why Cécile Cassel shouldn't be even more famous than the rest of her great Gallic family.

Hair by Bruno Silvani at Jed Root Paris. Make-up by Marco Latte at B Agency Paris. Fashion assistant: Ashley Fletcher