Last year she confronted the now sacked Daily Mirror editor Piers Morgan in his office about his newspaper's treatment of her. For a picture of Charlotte smoking a cigarette, thousands could change hands. For the "exclusive" story of her first kiss and even her newly surrendered virginity, that figure would be multiplied tenfold. She has grown up in the crossfire of relentless long-lens interrogation.

"Every time I said something to him like 'Did you not appreciate the fact that I was, like, 13 or 14 at the time — didn't that matter to you?', he was like, 'Oh, stop moaning, for God's sake. All you celebrities do is moan.'" She wasn't moaning, she was challenging and, for once, Morgan appeared to be squirming. What parent — Morgan among them — would want their child's every misstep or embarrassment exaggerated and witnessed by millions? He seemed at a loss to explain why a 13-year-old girl should be fair game for his newshounds.

In the tabloid world, Church's voice and music were marketed and thus ordained as angelic seven years ago, and therefore their owner, the pretty, clean-cut, working-class little-girl-with-a-gift had a duty to portray the character traits of an angel. Now, as a sexy, sassy 18-year-old, the owner of that image is policed around the clock, without parole, allowed neither teenage angst nor hormones, nor, especially, a T-shirt that reads: "My Barbie is a crack whore".

It was inevitable that when Charlotte found a boyfriend, lost her virginity, got tipsy, swore, showed cleavage, the angel's fall from grace would fire brimstone from the tabloid's pulpits.

Maybe because she's sold 10m albums. Possibly because she's met the Queen twice, sung for George W Bush and the Pope. But mostly because Charlotte Church is "a good story". She's made millions from a name and a voice, and when she jumps headfirst off the pedestal of fame into an everyday teenage existence, it makes great headlines.

It reached its climax this summer. Church had a holiday in Ibiza with friends and, like almost every other 18-year-old girl, she had fun. It earned her the Daily Mail headline "The Vices of an Angel".

The Mail "revealed" that she drank alcohol with her friends, smoked, danced, partied and — horror of all horrors — ate mostly chicken and chips. Like any other young woman growing up, she is experimenting with independence, yet in those constant and ever-present reprimands may lie her successful transition. For the Mail is doing her a favour. Church's career is going through a difficult metamorphosis, from angel to Madonna, a would-be international pop star. In defining her behaviour with such parental opprobrium, the tabloids are introducing her to her peers and "customers" as "one of us". Their attempts at demonising her are in fact humanising her; the "vice of an angel" may be seen as the "voice of a generation".

On her 18th birthday earlier this year, Charlotte Church would have been forgiven for wilting under the relentless pressures of celebrity, schedules, flashbulbs and betrayals. She could have locked herself away. Instead, she went out on the town with friends — defiant of the paparazzi. "It goes with the turf," she says, with the aplomb of a seasoned and fearless heroine in the front line of celebrity.

She laughs easily and has a coruscating sense of humour. On weekends she sleeps late and cleans her house. Her best friend, Naomi, whom she sees every day, says: "How many millionaires do you know who get down on their hands and knees and mop their own floor?" Only when she's had a fight with her mum at the same time that she's in a fight with her boyfriend, Kyle, does she appear to be upset. She has close friends from her childhood, the support of her family, a maturity beyond her years, and a stoicism unusual in one so young; she is a fighter, and she has a bigger battle than with the tabloids on her hands. She's not preoccupied with what she's been through but focused on where she goes from here.

For the past two years, a constant feature in the short life of Charlotte Church has been the question of transition; a transition that so many before have failed. Can she survive the leap from child star to adult performer, and can she navigate safe passage from adolescence in tandem with, or in spite of, success or failure?

She has a different kind of fame. She is not just another cute adolescent celebrity with shiny hair and flawless skin. She has, and has had since the age of 11, a remarkable talent. A voice that has catapulted her into a rarefied and dangerous area of fame: the archetype of the child wunderkind.

Such prodigies have been seen to falter when they've dared to grow up. A fall from grace does not take much: a drunken tumble, a night out with the wrong man, an inadvertent outburst, a struggle with dependency. Will Church cross both thresholds and thrive?