Charlotte Gainsbourg's half-sister: The darker daughter, Lou Doillon, comes out of the shadows

It hasn't been easy being Lou Doillon, 30, the daughter of Jane Birkin and the half-sister of Charlotte Gainsbourg, Serge's daughter. “We all lived in a bit of a mad house,” she says. But now, after years of living in the shadow of one of France's most famous families – “I couldn't have gone on smiling at their premieres or awards shows while nothing was happening in my own life” – she has just released her debut folk album, Places, in the UK, having won Best Female Artist at Les Victoires de la Musique, the French version of the Brit Awards, a few months ago, making history by winning it with a first album.

Today looking very stylish, Doillon, who was the face of Givenchy, is dressed in black with a cream blouse and foppish cuffs with a giant-brimmed hat. She has come on a day trip to London from Paris, where she lives in the bohemian district, Bastille, with her son Marlowe, 10. She talks without holding back – in perfect English – as she does on her album of confessional folk songs about love, regret and obsession.

The songs are presented in a sophisticated and broken husky voice – with an American drawl: “I.C.U.” is about missing somebody; “Same Old Game” is about betrayal by a man; and “One Day After Another” is about getting off the merry-go-round of life to take time over things, which is certainly what Doillon has done.

The daughter of indie film director Jacques Doillon, she says that, for the last 10 years, she has lived largely as a “recluse” in Paris – “we can do that in France due to the strict French privacy laws”. She would not have done anything with her songs had not her mother's friend Etienne Daho, a singer and record producer, visited her little house, which is painted black inside with books everywhere, and convinced her to let him produce and record her album last year.

“All I wanted was for it to be recorded in the minimum of time at a crummy place near to me with no superstars on it. We did it very quickly in 10 days.”

Her mother is now “my biggest fan,” she says. “She is very sweet about it and says that when she gets on stage to sing she now has my songs in her head.” Her sister Charlotte is still getting used to not being the only sibling in the limelight. “Charlotte was slightly taken aback when somebody stopped her on the street to talk about my album. I told her: 'I've had to put up with this for the last 30 years – I can't walk a metre without somebody talking to me about you. You are going to have to get used to it as I'm not going to stop singing for sure.' It changes the dynamics in the family. It takes a bit of time for the rest of the family to adapt.”

So, after years of feeling like an outsider, Doillon, who has now finally won over the hearts of the French people, is basking in her own success. As a child she felt like “Joseph Merrick the Elephant Man” in her family. “My family were in the press a lot and I think my mother tried to hide me to protect me, but it makes you wonder, 'why they are all hiding you?'. She became rebellious aged nine with dreadlocks, then piercings, tattoos, and tons of make-up, which was a horrifying vision for her chic family. She quit school at 15. ”I guess I started wanting to be the Christmas tree so that people would notice me,“ says Doillon.

Her childhood in Paris was intense, with too many larger-than-life characters in one family – “but a lot of love”. Serge Gainsbourg, her mother's former partner, whom Doillon called “Papa Deux”, was always at home with them despite the fact Birkin was with her father. She lived with Charlotte and photographer Kate Barry, from her mum's first marriage to the James Bond composer John Barry.

Her father left Birkin when Doillon was eight, after Serge Gainsbourg died, because Birkin was consumed with grief. On her father's side she has three more half-sisters – film director, Lola, 38, student Lili, 18, and Lena, two.

But, despite spending all her school holidays in the UK staying with her uncle Andrew Birkin and her cousins at his farm in North Wales and his London house in High Street Kensington, or with her late grandmother, the actress and Noel Coward's muse, Judy Campbell, in Chelsea, she no longer spends any time here.

“I live like a strange immigrant in France – we only cook English food, my son speaks English and drinks Horlicks before he goes to bed. My mother is completely integrated as a French woman and she has a French flag in her house. As soon as I arrive in England, I feel very foreign and French.”

It wasn't until Doillon had therapy that she realised she was “raised to be a muse”. She has since broken the pattern after dealing with heartbreak when the musician Thomas-John Mitchell left her less than a year after their son Marlowe was born, and she has emerged more like “one of the men in her family” – a creator, not a muse.

Doillon began acting aged six, playing her mother's daughter along with sister Gainsbourg in Kung-fu Master!. Her dad cast her in a juicy role in Trop (peu) d'Amour aged 14. But now she has decided to call it a day with family collaborations because it has “hurt both my parents”. “My mother put me in her autobiographical directorial debut Boxes in 2007 and my dad cast me in his movie Me, You and Us [A Child of Yours] last year to help get me back into movies recently – I told them: ”Stop! Go and find another actress. It doesn't count with critics because I am your daughter.“

She was a self-imposed “hermit” for more than 10 years when, at 19, her life changed when her cousin Alexander Birkin, known as Anno, to whom she was very close, was killed in a car crash in Milan, along with his band Kicks joy Darkness, and she got pregnant. “I lost everything at 19 – the movie industry turned their back on me – at 20 I was stuck in a house like a little granny with a child in my arms.”

She survived by reading her favourite letters by French poets by chandelier-light at theatres across France for a few years, as well as the odd well-paid fashion campaign. She also wrote songs, but never with the ambition of getting them heard. “Now everybody stops me in the street and says, 'Keep on going, don't stop making music, we love you”.

Lou Doillon's 'Places' is out now

*This article appears in tomorrow's print edition of Radar Magazine