The dictionary definition of the word diva is "a very successful and famous female singer." Mariah Carey is certainly that. In fact, she's the biggest female artist of all time, with a tally of number one hits rivalled only by Elvis and The Beatles.
Her glass-shattering voice is not to everyone's taste (Cameron Diaz once said: "If you really want to torture me, sit me in a room strapped to a chair and put Mariah Carey on, over and over again.") But no one can deny that it's an extraordinary gift.
When the word diva is applied to Miss Carey, however, it refers to more than just her vocal abilities. To put it tactfully, she has a reputation for being one of the most high-maintenance artists around. She is never without an enormous entourage, and red carpets are reportedly rolled out the moment she decides to leave the house. She once allegedly asked for puppies to be provided backstage, as their presence would calm her nerves. And, most famously, Miss Carey doesn't "do" stairs.
Our interview, therefore, is something of a surprise. For a start she turns ups early most un-diva-like behaviour and then apologises for her timekeeping. Could this be the same Mariah Carey who supposedly throws a strop if her hotel room isn't painted a particular shade of pink? Clearly not, as she quickly assures me that her life is not as glamorous as people think. She sometimes buys her own groceries, she says, and likes to escape from her entourage just to be "normal."
But she doesn't mind being called a diva. "Everyone's a diva these days. You don't even have to be a singer. If a woman opens a foodstore she's the Deli Diva. Some people use it to mean a bitch or whatever but I grew up with a mother who was an opera singer and it was used all the time in another context."
She's a sweet girl (definitely not a woman, even though she's 35) and seems more able to laugh at herself than your average Stateside celebrity. Every now and again she does a sort of camp 1920s accent, peppering her sentences with "daahhling" and "my dear" in her naturally smoky voice.
When I ask about the red carpet demands, she jokes that she walks on red carpet in her own apartment "and people throw petals in front of me at the same time." As for the stairs: "It's, like, totally the opposite. I don't even like taking the elevator. I've stayed in so many different places all over the world and I've been in too many that break down so I prefer stairs. My security will be panting after I've made them walk eight flights."
But for all Miss Carey's efforts to sound like the girl next door, she acts like royalty and she knows it.
Before our interview Mariah was working out with her personal trainer, whom she flew over from the Caribbean. "My trainer is French and she lives in St. Barts," she says. "My friends are like, 'Only you would import someone from St. Barts to come to New York or LA.' But I say, 'Well, I can't be spending all my time in St. Barts. I mean, I'll never get any work done.'"
It's difficult to begrudge Mariah the perks of fame. After all, she hardly had the best start in life. Her father left the family home when she was three years old, and she spent a poor and unhappy childhood on Long Island, New York. As a mixed-race chld, she felt she could never be part of the gang with her black or her white peers.
She had an older brother with cerebral palsy and a troubled gymslip-mum sister who contracted HIV. Her maternal grandparents, who were white, were not best pleased by Mariah's mother's choice of a black husband and ostracised the family.
None of this stopped Mariah or more to the point her mother from having big ideas. This girl was born to be a princess. "My mother named me Mariah Carey as a stage name," she says. "She felt this was what I was going to do."
Mariah's voice was her passport from poverty and misery and it has delivered on the former, if not the latter. "My voice was my secret. That was my thing," she says. "Whatever the problems were, I always knew I had that. I don't know what my self esteem would have been like without it."
Pretty low, presumably, since Mariah still feels like an outsider even today. "I'm still the same girl who came from a meager upbringing and a pretty difficult childhood and with an inferiority complex. But the fact that I'm able to live my dream is an enormous gift."
The man credited with making Mariah's dream come true is Tommy Mottola, formerly chairman of Sony Records and one of the most powerful men in the music industry. When, at 18, Mariah met him, he must have seemed like a godsend. Not only did he want to make her a star, he wanted to marry her, too.
The couple had a lavish wedding (the dress had a 27ft-train) and an even more extravagant lifestyle. Their house had two swimming pools, twelve bedrooms, a recording studio and a heli-pad.
Mariah's career took off, on the back of hugely successful ballads and belters such as Herto and Dreamlover. There was, however, a price for this fairytale. She claims that Mottola, 20 years her senior, was obsessive and controlling. He wanted to engineer every aspect of her life. She says he would call her to check up on her. She wasn't allowed to look or sound "too black" and she was told to dress demurely.
The marriage, predictably, didn't last. And after it ended, Mariah's career also seemed to hit the buffers. Sony lost interest in her, she signed a new deal with Virgin, but was then paid to leave. She attempted a film career, starring in a total turkey called Glitter. Then there were rumours of a breakdown and her reputation as a bonkers, demanding diva was sealed.
But you can't keep this girl down, and Mariah's latest album, The Emancipation of Mimi (that's her nickname, by the way) is a spectacular return to form. Both the album and the single We Belong Together have reached number one in America. And this, she believes, is her greatest achievement yet. "It's the first time I've had this experience and actually been able to enjoy it. It's something that I've done on my own."
The album title is well chosen. In the videos and publicly photos she's wearing a slinky, black Dsquared dress revealing acres of golden flesh a far cry from the wholesome image Mottola tried to create for her. "In the beginning, I was pretty much told what to wear," she says. "It was even drummed into me that I only looked good from one side and with my hair a certain way. So just having a shot facing the camera is a big deal."
These days she's more famous for her spaghetti-strap vests, and micro hot pants teamed with heels and a jaunty baseball cap. "Initially that was rebelling, but I have more confidence now," she says. And yesterday the seal was set on her comeback when she played at the Live 8 concert in Hyde Park. "I was thrilled and honoured when Sir Bob Geldof asked me to take part in this historic event," she says.
Like many American A-listers, Mariah speaks the language of the therapist's chair. But she says it's her faith in God that has pulled her through. "I truly believe that everything I have is a gift from God and everything happens for a reason. I had to go through a lot of things to get to this place the best I've felt in my life emotionally and creatively."
Those "things" don't, she says, include a breakdown. "That was something that was so highly sensationalised in the media. I remember sitting with some friends on a boat in Puerto Rico while newspapers were saying I was in a hospital somewhere. That was the first time I felt famous I had the press camping outside my home and photographing me in my pyjamas. But it's part of the package you have to take the rough with the smooth."
That doesn't mean she's happy to reveal her secrets. A three-year, on-ff relationship with Latin singer Luis Miguel, 34, ended early this year, so I ask who she's dating now. "Daahling, I'm married to my music," she says, huskily.
That's a joke, of course, but there's no doubt she loves being a very famous and very successful singer. Mariah Carey is a diva in every sense of the word but when you've sold 160 million albums, aren't you allowed to be?