Leona Lewis gets the Xmas Factor

It is a truth universally acknowledged that any diva worth her salt must record, at some point in her career, a Christmas album. Call it the Mariah Carey effect, or the perils of having Simon Cowell for a boss, but Leona Lewis, X Factor winner 2006 and, to date, the show's only international superstar, was never going to escape this particular fate. It features versions of both “Winter Wonderland” and “White Christmas”, and is called, to avoid ambiguity, Christmas, With Love.

“Yes, but I have really always wanted to record one,” she insists, laughing. “I've always loved Motown, the Ronettes, Phil Spector.”

To her credit, and despite the mandatory reliance upon sleigh bells, it isn't as cheesy as it could have been, and could well go on to soundtrack December afternoons in Starbucks for the next decade. Halfway through, it features something unexpected: the 28-year-old's rendition of “Ave Maria”, in full operatic mode. It's impressive.

“Well, I did train in opera initially,” she points out. “I didn't actually switch to contemporary until I was into my teens. I wanted to be a classical singer originally.” This is something she has communicated to Cowell, she says. “I told him I'd love to make an opera album, and he was like, 'yes, you should, at some point, blah blah blah, whatever'. But I don't think he took it seriously.” She smiles, pertly. “Perhaps he will now.”

The diva, resplendent in red tartan jacket, is sequestered for the day in a London hotel room, where the vibe – as dictated by a record company keen to remind visitors of the Christmas theme – is forcefully seasonal. There is untouched eggnog in a jug on one table, ignored mince pies on another. Lewis peers at the latter witheringly. “Never did like mince pies,” she says.

She is more ebullient in person than you would perhaps expect from the singer of such overpoweringly beseeching ballads. Over the course of three albums now – Spirit (2007), Echo (2009), Glassheart (2012) – the Brit School graduate from Hackney has come across as the Whitney Houston of “I Will Always Love You” rather than the Whitney Houston of “I Wanna Dance With Somebody”. Her voice, a powerful instrument, is always set to maximum quaver, and she is adept at singing a lyric into submission. Not just on her signature song, “Bleeding Love”, her 2007 single that reached No 1 in over 30 countries, but in everything she has ever done. In 2009, for example, she transformed Snow Patrol's indie anthem “Run” into a totemic weepie that could have sunk the Titanic. Away from the microphone, however, she is refreshingly down to earth, funny, and at great pains to dismantle the diva tag.

“I've done everything I can over the past seven years to remain completely normal,” she says. “When you're on the road non-stop, you do have people to do everything for you, but I insist on doing them myself. I need to remain normal. Okay, I can't travel on the tube, and, no, I don't have an Oyster card, but I don't want to forget how to post a letter. I remember reading Robbie Williams saying that he forgot how to pay a bill himself because he hadn't done it for so long. I keep telling myself, that's never going to happen to me. Never!”

For the first three years after X Factor, she was forever on the road. But because her fame had been TV-derived, those years were spent not touring venues but rather TV studios. “I would do two TV shows a day, singing one song – often the same song – for two-and-a-half minutes,” she says. “That gets dispiriting after a while. I wanted a proper tour; I wanted to get back in the studio. So after a while, I just said no; I stopped.”

Still hounded by paparazzi, she was portrayed as a latter-day Greta Garbo, pleading to be left alone. “I remember one time deciding to do something with my hair,” she recalls. “I dyed it, had a fringe, and the reaction was just insane, mad. Oh my God! She's changed! A fringe! She must be a seductress now! That was it for me, the point I decided I would never read the papers again.”

She started to spend more time at her home in Los Angeles. It was here she took control over her recording schedule. While her record company wanted an album a year, her approach made more sense: to release when ready. Glassheart, her third, she delayed by a full 12 months. When it eventually came out, it did not sell as well as Leona Lewis records are expected to sell.

If this bothered her, she hides it well now. She clearly loves her music, but she talks with far more animation about Hopefield, her animal sanctuary in Essex, where she keeps 200 rescue animals, including a two-legged llama. In LA, she has a horse, and a rabbit she liberated from a tramp on Melrose Avenue (she gave the tramp $100 for it), while at her London home she has two dogs, souvenirs from a pregnant mongrel she saved from the street. “I can't help myself,” she giggles.

It's this love of animals that keeps her vegetarian, though she suggests health reasons, too. “Meat is associated with cancer and all sorts of diseases,” she says, which is why she tries to keep her German choreographer boyfriend vegetarian too: “He tells me he doesn't eat meat when he's not with me, and I believe him, I think.” She doesn't smoke, rarely drinks, frequently meditates, and practises Bikram yoga, after which, she says, “I feel I can conquer the world.” Several times over the hour we talk, Lewis mentions her “mystical unicorn land”. She's not delusional, she knows it's not real, that it cannot be real, but you sense she'd like it to be nonetheless, a place far from the madding crowd, far from paparazzi and the Daily Mail obsessing over the size of her thighs.

“Simon has always told me to trust my instincts,” she says, “and so that's always what I've done. I'd love to sing for the rest of my life, but if my celebrity disappears tomorrow then I'll be completely fine with that, I really will.”

'Christmas, With Love' by Leona Lewis is released on 2 December