Jane Birkin is the voice of one of the most famous female orgasms in history, moaning breathily on the 1969 hit “Je T’Aime … Moi Non Plus” with her lover, the notorious French singer Serge Gainsbourg. It outraged the Pope, was banned by the BBC and, inevitably, went to No 1. But scientists said recently that the “copulatory vocalization” that Birkin had unwittingly influenced generations of women to emulate didn’t necessarily correlate with female pleasure.

“I heard that,” Birkin, 75, says in her Pathé-newsreel-meets-Paris tones. “All I can say is at the very beginning with Serge we’d be in sort of prostitute hotels and people were afraid I was being murdered. We had very worried proprietaires knocking on the doors saying, ‘Get the little one out!’ — they thought I was under-age, because I was making so much noise. I remember saying, ‘We’re probably the only people in this brothel who actually love each other.’ So we were chucked out and went to make as much noise as we wanted in our chic hotel in the Sixth Arrondissement.”

Jane Birkin is back with a new album, Oh! Pardon Tu Dormais.

Gainsbourg and Birkin met when she was 21, having escaped Chelsea for France with her toddler daughter after a brief, “cold and unsuitable” marriage to the James Bond composer John Barry. Gainsbourg, 18 years her senior and the father of her actress daughter Charlotte, now 50, introduced her to not only orgasms but superstardom in Paris, where she has lived ever since. More than 40 years, two serious boyfriends and another child have intervened since their split, yet he still appears to loom larger than anyone in Birkin’s life.

“Writers and composers often take themselves very seriously; they’re certainly not the sort of person that has that irresistible thing of making you laugh. But Serge did. He carried a little book of the latest jokes in his pocket, [and] he’d say, ‘Have you heard this latest Belgian-Jewish joke?’ That’s rare, I don’t know whether Bob Dylan has a cracking sense of humor and jokes in his pocket, but I doubt it.”

The pair partied every night, getting home in time to take Birkin’s daughters to school then sleeping until pickup time. Eventually, however, the boozing, and the sense that she was his plaything, paled. “It became monotonous when every single night at 5am Serge couldn’t get his key in the lock and became quite nasty and so you’d give him a shove from behind. He was very dominating. We lived in a beautiful black house and he decided everything about where things should and shouldn’t be. I’d have to take the children to a house in the country so as not to be bossed about anymore.”

Birkin was 18 when she married composer John Barry.

She left him for the director Jacques Doillon, with whom she had her third daughter, Lou — now a renowned singer. “It was like going into a monastery; Jacques didn’t drink or smoke. It was so nice for the children to set off with their bikes to the Bois de Boulogne, quite a different sort of life. But I could hardly believe on New Year’s Eve we weren’t going to go out to Maxim’s to throw confetti at the waiters, but just sit, watching the clock until it was midnight. It was so still.” Which type of New Year did she prefer? “Throwing confetti at Maxim’s …”

Still, the exes remained close. “Serge became the very best friend; friends we weren’t when we were a couple. You’re very grateful that somebody wants to keep on with you, even though you’ve left them. I couldn’t believe it when he actually turned up for dinner, even when he was with [his partner] Bambou [von Paulus]. My family didn’t mind and his family didn’t mind.”

Gainsbourg and Barry are dead; so is Birkin’s oldest daughter Kate, who, after a long history of depression and addiction, was killed falling out of a window in 2013, aged 46. “The most shocking thing that happened to all of us,” Birkin says.

“I remember saying, ‘We’re probably the only people in this brothel who actually love each other.’”

Suicide was suspected but never proved. In her latest, very personal album, Oh! Pardon Tu Dormais, there’s a haunting number called “Cigarettes” in which she wonders if Kate opened the window to clear the smell of smoke. “Maybe it’s an accident, really dumb, who knows?” she sings. In “Ghosts,” she recalls “grandpa, grandma, mother, father, daughter, nephew, cats, dogs, husbands and friends”, all gone.

“Serge became the very best friend; friends we weren’t when we were a couple.”

Birkin had a minor stroke last year but is fully recovered. “My very best friend Gabrielle Crawford [the former wife of Michael Crawford] spotted something was wrong. I’d just come home from doing a show in La Baule, hadn’t noticed anything, nothing went wrong with my arms and legs or face, but she thought I looked unsteady. She’s a very cautious girl and as she knows me very well — I was banging on about wanting a club sandwich at 8am and I fell over quite a lot — I’d thought I’d fallen over Bella [her dog], but she thought I looked more unsteady than that. Then I dropped all the glasses, but I’m naturally clumsy, so I didn’t notice. But she got me to hospital quickly, so I was very lucky. I didn’t have anything serious happen to me at all.

“I live in a panic that things will happen to friends; all around me people are falling like ninepins. I just feel very lucky to be able to walk down the street and do my own shopping and be independent.” Does she have a regimen to maintain her health? “No.”

With her daughters, Lou Doillon and Charlotte Gainsbourg.

She’s talking on the phone (Zoom bamboozles her) from her flat near Boulevard Saint-Germain. Her daughters and five grandchildren live nearby. “But often I have to look at Instagram to find out what they’re doing — I hate it and I hate texts and those little smiley faces.”

Always heralded as the embodiment of Parisienne chic, today she’s wearing old black trousers and a cashmere “jersey” (a very Birkin word) over a T-shirt. She’s just designed a collection for the French brand A.P.C. “There’s a pair of trousers with really deep pockets, so you can carry everything; much better than holding on to a very heavy handbag.”

But what about the Hermès Birkin bags, named in her honor, beloved of WAGs and retailing for as much as $288,000? “I’ve got one, but I only like them when they’re black and very simple. The crocodile ones or the brightly colored ones I don’t understand at all. And you do need someone to carry them. When I go on tour my assistant is my bag-carrier; without one of those you get tendonitis.”

Birkin with Jacques Doillon and Le Club Régine’s Régine Zylberberg at the nightclub in 1981.

Since her last relationship with the writer Olivier Rolin ended in 1996, she has been single and pleased to be free of the intense jealousy she suffers. “The fears always creep back — if they’re doing a movie everything’s so dangerous because people are so much more attractive than you. It’s a relief not to have to torment yourself with stuff that gets you nowhere. Even your face looks all twisted and horrid. When you see yourself in the mirror you think, ‘Crikey, I wouldn’t come back to a face like that.’ ” She’s much happier with Bella, a bulldog. “It’s just lovely. You don’t bug dogs all night long saying, ‘I’m sorry!’ because you’ve been angry about what time they came home. All you hear is their gentle snoring and you’re soothed.”

“I’ve got [a Birkin bag], but I only like them when they’re black and very simple.”

Why was such a beautiful (and talented) woman so chronically insecure? “I think everybody’s got [insecurity] a bit,” she says, which isn’t an answer. In the past she’s said it’s because she was bullied for being flat-chested at her Isle of Wight boarding school and was always compared unfavorably with her glamorous actress mother (her father was a Royal Navy war hero). Now she simply gives another example of poor self-esteem, saying she recorded “Je T’Aime … ” purely because otherwise she feared the gig would go to Brigitte Bardot. “I thought, ‘Oh, crikey!’ because I had seen pictures of Serge and Bardot snuggling up in a sort of telephone box, so when he asked me of course I said yes immediately.”

Today, she spends a lot of time at the cinema because she hates watching Netflix at home toute seule. “Watching things alone is like w***ing,” she says crisply. “Afterwards you just feel tired, because you haven’t shared anything with a friend.” Clearly, in her dotage, Birkin still knows how to épater la bourgeoisie.

Julia Llewellyn Smith is a regular contributor to The Times of London