Katherine Jenkins: Confessions of a choirgirl

When Katherine Jenkins's PR tells me the singer is an open book, I smile gamely, but something inside me twangs and I raise my inner eyebrow. Because while Jenkins is many things – mezzo-soprano, classical crossover star, forces sweetheart, "nation's darling" – her image does not scream candour. Her job is to appeal to an army of fans who otherwise rarely buy music (sometimes referred to as "the massive passive"), an audience that stretches from babyhood to 90-year-olds, who have fervently embraced her image as a modern-day Dame Vera Lynn in ankle-snapping heels. Consequently, her career rests on supreme sweetness and ultra-femininity. Not an obvious recipe for straight talk.

We arrive at her palatial hotel suite overlooking the Thames, and she enters in an outfit that does nothing to dispel my fears. Vertiginous beige platforms teamed with a blindingly pink, full-skirted dress, and impressively full makeup. I gulp and then I notice her short, black-painted fingernails. They offer a glimmer of hope.

It soon becomes clear that, behind Jenkins's fluffy, girlish image is an appealing steeliness; yes, she's controlled, but she's certainly not unfriendly. She has been called ruthless, but I suspect it would be fairer to call her driven. When I ask about this, she refines the word to ambitious, "with a sensible side, rather than just [aiming for] global domination". She has always worked incredibly hard. On first securing a record deal, she heard that 19 out of 20 recording artists are unsuccessful and did everything she could to be in that golden 5%. Her commitment paid off: she once occupied the top three places in the classical charts at once.

Jenkins is known for being hands-on with every decision; she presides over not just a concert's repertoire, but the poster and programme, too. She also has a reputation for being demanding. In 2008, for instance, it was reported that her rider (a list of backstage hospitality requests) for an appearance at a literary festival included three old towels, cans of coke to be served at very specific temperatures (room, cold and – illustrating the confusing levels of specificity here – chilled), and six vegetarian meals dished up at half-hour intervals. She laughs when I ask about this and lilts: "Who asks for old towels? These things get blown out of all proportion … I don't eat six meals in three hours. I think maybe because of the kind of music I sing, people want to believe you're a diva. They can't believe after eight years, and eight albums, you're still relatively sane. I feel like they almost want me to throw something at somebody."

She was indeed rumoured to have thrown a mobile phone, after her record company dared criticise her makeup. "I would never throw a phone," she says firmly, before asserting that her most extravagant request is Green & Blacks chocolate. She starts speculating about her next rider. "Maybe I should just be like, I need everybody in colours of pastel, I need pigs with bow ties, and every time I walk on stage and see the sound man, he needs to mime, 'You look fab-u-lous, darling.'" Big pigs or micro-pigs? "The cute little ones, of course."

Her new album, Daydream, is a melange of easy pop and traditional folk, with I Dreamed a Dream sung in French for good measure. It won't be to everyone's taste. The critics of classical crossover are notably biting; David Mellor, the former Tory MP turned music critic, once called her interpretation of a song set to Holst's Jupiter "bathetic rubbish" and "vomitacious". But on the album's more traditional numbers her voice is pleasant, with a warmth that speaks of Christmas afternoons drinking mulled wine, playing Scrabble with a squiffy aunt while the Antiques Roadshow whirrs on TV.

When she switches to pop numbers, this selling point – the sheer cosiness – falls away. Her pop voice is surprisingly bland. Jenkins moved from Universal to Warner Music three years ago, in reportedly the biggest classical recording deal in history – said to be £5.8m, although Warner later claimed this figure was inaccurate – and there was talk of her breaking into the US (it hasn't happened yet).

It's the first minor delay in a genuinely impressive ascent. Jenkins grew up in a council house in Neath, Wales, with a father who worked for a box factory, and a radiographer mother. Her father was in his 50s when she was born, and retired when she was six; he became a house husband, and was incredibly close to Jenkins and her younger sister. In her 2008 autobiography Time to Say Hello, she describes a life filled with church, schoolwork and second-hand Barbies. "I just have very feminine tastes," she writes. "Netball, forget it (I worried about breaking a nail)." She began singing in church choirs, and had soon won Welsh Choir Girl of the Year.

When she was 15, her father died of lung cancer, aged 70. Jenkins, a Christian, says she believes "in heaven. I believe my dad is somewhere doing something nice. I feel I've been too lucky to travel this far without somebody guiding me." Later in our conversation, she says, with a hoot, that she found it hard to identify with the character she played in Doctor Who  last year: a woman who had been frozen in a cryogenic chamber. "I thought, 'Where do I draw on my own experience for that?' But with the parts where she's devastated because she knows her time is running out, I thought, 'Well, I've experienced that with my dad.'"

Her GCSEs came just after his death; she achieved stellar grades, then passed four A-levels, and won a scholarship to the Royal Academy of Music. What was her ambition while studying? "I thought I'd get to about 30, maybe get into an opera chorus, and slowly work my way up." But, towards the end of her course, a producer friend made a demo, which was passed to Universal, and they signed her up for six albums.

Her dream of being a serious opera star was set aside, although she has talked of wanting to sing Carmen in her 30s. She is now 31 and still believes it will happen: in fact, she's off for a singing lesson this evening. Does it annoy her that there's such snobbery towards classical crossover singers, a notion that they're somehow undermining the operatic tradition? "Everyone's entitled to an opinion," she says tightly. "But I disagree with it. I think they want to keep [opera] small and elitist, and I think it should be for everyone."

The stories of her years at music college reveal someone simultaneously more tough and more vulnerable than her public image. In her autobiography, she writes about fighting off a would-be rapist in the street; and about an eating disorder that saw her weight drop to less than seven stone. She now says: "Disorder is too strong a word. I was just using food in a strange way, following silly diets, and then I think I made myself quite ill."

Famously, she also took drugs. This emerged three years ago, when a friend approached the newspapers with a video reportedly showing Jenkins drawling: "I am fucked." She pre-empted this story with a tell-all interview in the Mail on Sunday with Piers Morgan, which is hilarious in its hyperbole. According to Jenkins's account, she was probably not much more debauched than the average student, but Morgan wrote: "Her life seemed to be spiralling out of control in a booze- and drug-fuelled haze" until she got "the break that would change her life for ever, and perhaps even save it".

'I thought it could end my career'

Was it a relief to talk about the drug use? "Yeah," she says, "because I think when you sing classical music, people almost imagine you've led a nun's life. I always felt pressure from that, because it wasn't something I was putting out there. And when I came out to talk about it, I really did think this could be a career-ending moment … [But] people's reactions were overwhelming. They said, 'We've all done silly things.' I don't have to live up to that whiter- than-white image any more."

Jenkins's submerged toughness has been useful. On her first visit to Iraq to perform for the forces in 2005, her helicopter was targeted by two missiles. "They had to do this – " She mimes rolling back and forth through the sky. "They set the flares off, and then they rock the aircraft, so it confuses whatever has been sent." She's determined to go out to support the troops again, though, wherever she's needed. Asked if she thinks western forces should still be in Iraq, she says: "It's really not about my political opinion. The troops don't get a say in where they go, and I don't get a say in where I have to go to support them. I have an opinion. But I wouldn't share it."

She is equally tight-lipped about her private life – Jenkins is engaged to former Blue Peter presenter Gethin Jones – announcing, before I've actually asked, that she doesn't really speak about it, and then talking quite easily about her hopes for children. I ask if her squeaky-clean image has ever bothered her; if she balked, for instance, at being called "Saint Katherine"? She seems genuinely shocked. "I've never heard that!" So you're not a saint? She shakes her head. "One hundred per cent not."