Rendez-vous with Mireille Mathieu in the bar of the Hôtel Bristol, luxury Parisian hotel and the singer's temporary HQ. Mireille is sitting curled up on a sofa that engulfs her tiny frame, looking exactly as you'd expected her to look: red lips smiling beneath that famous black fringe, chatting away to her sister Matite in her inimitable southern French accent. Fads and fashions may change, but Mireille will always stay the same – a reassuring heritage, a fixed point of reference, something to cling on to as we are swept along in the swirling current of our fast-moving world. Other, more fickle, stars may change their image to keep up with the seasons, but Mireille has confidently sported exactly the same look for the past four decades. And why change it now, with only a hint of wrinkles on her 20-year-old face?

Don't be fooled by appearances, though. Mireille Mathieu, the leading ambassadress of French 'chanson', is about to celebrate forty years in the music business. And she's doing it in style, bring out album number 38 and making a live comeback at the Olympia, in Paris, in November of this year. The moment has come to look back over four decades of recording, touring and live performance filled with emotion, voyages and encounters. The moment to take stock of what it means to have forty years of career behind you. "I don't like the expression 'taking stock' though," insists Mireille, "It's got a sad ring to it! Personally, I still feel like the whole adventure started yesterday. The early days of my career are still fresh in my mind. I might be celebrating forty years of my career today, but when it comes down to it that doesn't mean so much, after all!"

The First Lady of French 'chanson' is, perhaps, still blinking, unbelieving, at what she still describes as "the fairy tale" that began on the set of the TV talent show Télé Dimanche on 21 November 1965. Mireille's performance that night catapulted her, the eldest in a family of fourteen, from her humble beginnings "manufacturing " envelopes and set her on the fast track to fame. A lucky break that might be compared to the fortunes of contemporary winners of Star Academy? "No, absolutely not" insists Mireille, "The Star Academy candidates aren't exactly fresh and innocent. There's no surprise factor for them. They know they're going to be filmed as part of the programme and that there'll be a winner at the end. It wasn't like that for me! As far as I was concerned, Paris was the other side of the world. I'd never been on a train before, let alone seen a camera! And I certainly didn't know when I started out where the whole thing was going to lead."

From the moment she had her rags-to-riches moment on Télé Dimanche, the Mireille Mathieu legend was born. And, surprisingly enough, the "fairytale" went on to last another forty years – although, one wonders whether those two scourges: routine and the boredom of routine, haven't crept in now and then. "I'm never ever been blasé about life," insists Mireille sincerely, "I savour every moment as if I were sucking a sweet or letting an ice cream melt on my tongue. I remember when I was at school I used to hate geography lessons. They were so boring. I used to sit there and think to myself 'Why in the world is the teacher standing there going on about New York and it being a typical boom town. What do I care? I'm never going to go there. Now, of course, I've been round the world and back and rubbed shoulders with some of the most famous people in it – and I can honestly say I'm still as amazed every time!"

Ask Mireille what the highlights of the past four decades have been and she promptly replies: "Every single moment!"  But then, on further reflection, qualifies that answer, citing her mentor, Johnny Starck. "I have to say, I had the greatest manager of all time!" Other obvious highlights include several meetings with the Pope. "I sang three times for the Holy Father, Jean Paul II, including once at a private audience with my mother. Of all the famous figures I've met in my life, he was the one that moved me most. He had the most incredible aura about him!" Oh, and then there was the concert at the Kremlin where she appeared on stage with 10,000 Russian extras and President Putin in the front row. "I was really touched by the Russian audience," remembers Mireille, "They showed me such affection and I found it particularly moving because they were living in such poverty."

Another favourite memory is the special Christmas concert she performed at the Vatican. "Each of the artists involved sang Christmas carols in their native language," Mireille reminisces, "They really threw themselves into it body and soul. It was a million miles from French variety shows where everyone performs in play-back!"  Then, with tears springing to her eyes, Mireille recalls another more intimate moment in France. "I was on a visit to Lourdes and these two mentally handicapped children recognised me and asked me to buy some cassettes for them. Then, as a thankyou, they performed their own version of 'Mille Colombes.' That has to be one of the best memories in my life so far. It's so simple to give!" Pulling herself together again, Mireille apologises for "getting carried away with my emotions. " Questioned about her supposed "abandon" of her homeland, an accusation journalists frequently fling in her face, the singer gets worked up again, however. "People should stop reproaching me on that score," she declares, "My country should be proud of me, like they are of their footballers who go off and play all over the world. France was the country where I hatched out of my egg - and then I learnt to fly with my own wings. But that doesn't mean I'll ever stop coming back to my nest!"

After forty years of chart success and international fame, one wonders what kind of woman you might become? Mireille's answer is short and simple: you stay exactly the same! And that's why her latest album bears the eponymous title Mireille Mathieu. "Do you think that sounds presumptuous?" she asks, "I didn't feel like inventing any other title. I thought 'Mireille Mathieu' sounded simple and straightforward." Interestingly enough, all the songs on the album were inspired by the Demoiselle d’Avignon's favourite subject, love. "The most universal theme there is," she muses, "The simplest of emotions, but the most difficult to describe."

Despite being an old hand in the studio, Mireille admits to feeling constantly plagued by doubt. "Before I go out on stage," she says, "I'm literally trembling with fright, but at the same time I'm filled with the most incredible sensation of joy – just like when I was twenty years old! But audiences aren't so forgiving with me today as they were when I first started out. And I have to admit, I'm my own worst critic. You know, Johnny Starck never once turned round to me and said 'that was great!' It's as if he's still sitting there on my shoulder!"

Sitting on her sofa at the Hôtel Bristol, surrounded by her sister and loyal manager Matite and her mother (whom she introduced on stage in Russia), Mireille appears to have her feet firmly on the ground. And what, may one ask, has helped her stay the course over the past forty years? "Faith," quips the singer, a self-confessed devotee of Sainte Rita de Cascia, the patron saint of lost causes. "Faith in other human beings and in God." Faith and the ability to recognise that "the most important thing in life is to do what you love with all your heart." Something Mireille Mathieu has put into constant practice in the course of the past forty years!