Pity festive churchgoers in the Welsh village of Neath; were it not hard enough staying in time during the hymns, they must also try to keep up with the trillings of the record-breaking, world-famous mezzo-soprano in their midst.
While much of her life now takes place in the States, every Christmas Eve Katherine Jenkins can be found “belting out a descant” in the pews her family have frequented since she was a child. It’s a tradition that no doubt reminds her how far she’s come.
It was here the classical crossover singer first developed her passion for music – and for the limelight.
She was seven when she started singing solo as a chorister. Jenkins then went on to join the National Youth Choir of Wales before winning a scholarship to the Royal Academy of Music aged 17.
In 2000, she signed a £1 million deal with Universal, reported to be the most lucrative in UK classical recording history.
Since then, the 32- year-old has crossed over not only into popular music but into acting (she appeared in the 2010 Doctor Who Christmas special), dance (she came second in Dancing With The Stars earlier this year) and entertaining troops; various trips to Iraq and Afghanistan have seen her take the “Forces’ Sweetheart”
baton from Dame Vera Lynn.
When I finally catch her, she is in LA, where she is performing on tour with tenor Andrea Bocelli. We have been allocated a strict 15 minutes – whether for the sake of Jenkin’s voice or the requirements of her schedule I never get chance to find out.
I have been forbidden to ask “any personal questions”, by which her management mean anything to do with her breakup with Blue Peter presenter Gethin Jones (the couple broke off their engagement at the end of last year) or the media stories in which the singer took the curious decision to deny, unprompted, having an affair with David Beckham.
Jenkins has always kept a tight rein on her private life; when dating Jones, she repeatedly refused to discuss any aspect of their relationship and sometimes to acknowledge it at all.
Even on the innocuous subject of her new Christmas album, she proves cautious.
I ask her about Moulin Rouge love song Come What May, her duet with Placido Domingo.
“Placido and I were looking for a song that’s well-known and well-loved, not strictly a Christmas song but one that could be adapted to Christmas.
“Its sentiment is that no matter what happens and how far away I am from you, I’ll always love you and you know, many people aren’t lucky enough to be together at Christmas.”
When I ask if the song has personal resonance, the answer is a curt, “Yes.” She won’t elaborate further.
But one doesn’t become one of the bestselling female artists of all time without exercising a certain degree of control and Jenkins has worked too hard to risk damaging her brand in any way.
“It’s hard work,” she says of her life. “I’m dedicated.
I’m away from home a lot and I miss a lot of occasions – birthdays and so on.
“But I enjoy what I do and the day I feel like I’m going through the motions is the day I stop doing it. Although I’ve been doing this for nearly ten years it’s an amazing opportunity and I have to make the most of all of it.”
Clearly, the singer is hugely driven. Her mother was the family breadwinner and she and Jenkins’ late father instilled a fierce work ethic in Jenkins and her sister Laura, a charity worker.
“I remember mum having a conversation with my sister and I saying, ‘It’s up to you what you do in life but if you work hard in school you’ll have a good job, nice things, or you don’t. But you can be what you want to be’.
“Mum was a good role model for us. My sister and I do completely different things but we both want to work hard and do our best.”
Her professional role models are a long list of powerful women – Maria Callas, Edith Piaf, Madonna, Adele – “I like big voices.”
But while her heroines may be legendary divas, Jenkins is infuriated by the frequent suggestion she fits in the same bracket.
Rumours of tantrumthrowing have hounded her throughout her career but she insists it’s nonsense.
“I think people want you to be a diva. When you sing a certain kind of music and are a female artist, people like to think you throw water bottles at people and have tantrums.
“It is annoying when you read that you’ve done things you’d never do but I hope that when I meet people they realise it’s rubbish. My mum always tells me that the people who matter know the truth.”
Despite having amassed a personal fortune, Jenkins remains cautious with her cash. Her parents were short on money growing up and any spare they did have was put towards singing lessons and the like for the two girls.
“I still think about money and try to be wise with it,” she says. “But I’m a shoe-aholic like any girl and I probably have too many clothes.”
Jenkins is probably as famous for her old-school glamour as her voice and she’s unashamedly girly.
“I’m a girly-girl – always have been. I’m really interested in fashion and make-up. Even as a teenager I wanted to be well turned out. I like to feel feminine.”
Does she think the music industry places too much emphasis on appearance?
“I think it’s a part of it.
Even in classical music, image has become so much more important than it was before.
“But it’s not a bad thing if you go to the opera now and there’s a dashing, handsome, prince who looks like a dashing, handsome, prince.
The move towards considering image isn’t a bad thing.”
Does she feel pressured to maintain her looks – that bombshell figure?
“I don’t feel pressured by anyone other than myself. After this year, I probably experienced pressure to put weight on.
“For Dancing With The Stars, I was training for 18 hours a day.
I ate everything under the sun but couldn’t put weight on because I was working so much.
“I’ve learned a lot about physicality and fitness through the show and that’s great – I’m training for a marathon in April.”
A marathon?! She laughs.
“You see? The person putting the most pressure on me is me.”
l Katherine Jenkins performs at Brighton Dome Concert Hall on Thursday, December 13. Call 01273 709709 * Katherine Jenkins: This Is Christmas is out now, £11.99