It is true that her singing voice doesn't compare with the likes of Whitney Houston and Mariah Carey; she is no Janet Jackson in the dance department; she frequently wears dodgy frocks; she has, perhaps, forgiven her love-rat husband too many times; and this latest business with the Guildford Borough Council over the underground swimming pool that she is determined to build is undoubtedly tiresome.

But none of that matters, because the point about Cheryl Cole is that she is greater than the sum of her parts. Her appeal is not in the strength of her individual talents; it's in the package she has created so masterfully over the past few years.

Right now, the soignee X Factor judge is unstoppable. Last Sunday, her debut solo single, Fight for This Love, reached No 1 in the charts, and became the fastest-selling single of 2009. Meanwhile, her album, 3 Words, released the following day, also opened in pole position. Why? Because people just love her.

The sassy 26-year-old has the British public eating out of her perfectly manicured hands but remains pleasingly overwhelmed by her latest catalogue of triumphs. "I don't really know what to do with myself at the moment," she says in that thick, rather deadpan Geordie accent.

"The single going to No 1 was amazing. If the album goes to No 1, too, then it is definitely party time," she said in an interview ahead of the release.

"It's strange to look back on myself even three years ago and to think that I've climbed the ladder. I've been lucky enough to get better and better. It's just bizarre."

I am among the millions who have tuned in to X Factor since she joined its panel in 2008, so perhaps I can explain the absurdly widespread attraction of Brand Cheryl. We love that she is jaw-droppingly beautiful. We love that she is forthright, and not afraid to laugh, cry, feel tense and get irritated like the rest of us. With those sparkly eyes and killer smiles, she is endlessly mesmerising.

If anyone has the X factor, it is Cheryl Cole. This is why her fans don't care that she mimed to Fight for This Love when she performed it for the first time on X Factor. It is why we forgave the hideous slashed trousers and military cap she wore while she did it. It is why people are snapping up her records, even though some critics have been lukewarm at best.

Braveheart

She looks as good as we dream of looking, and the impression she gives is upbeat, feminine, feisty and fun. Plus, the girl has guts. It is brave to launch yourself as a solo artist when you are used to the comfort and safety of a group (the wildly successful Girls Aloud, beloved of everyone from hysterical tweenies to the smug marrieds who should know better).

"Being on my own, and not having the other girls on the [X Factor] stage, was scary. They were in the audience, but that was even weirder. It was definitely the scariest performance I've ever done."

It must be even more nerve-racking to have your career appraised by the same strict standards that you employ yourself as a professional judge of pop artists. How did it feel when the tables were turned? "That is a little bit unfair," she shoots back. "Because they are not artists, they are contestants. And I have been through that process myself [in 2002, on Popstars: The Rivals, where she won her place in Girls Aloud]."

Then, at 19, she beat off heavy competition on the reality TV show to become the pop star she'd always wanted to be. Girls Aloud have gone from strength to strength and are far from finished. But they have supported Cheryl's pursuit of a solo career. "They love the album," she says.

Cheryl's husband, Chelsea footballer Ashley Cole, adores it, too; he went out and "bought himself" a copy, and plays it in the car all the time. I've listened to 3 Words on repeat ever since I got my hands on it.

Listens to herself

The record has an unexpectedly strong R&B vibe — was that a deliberate move away from the perky, girlie, pop genre that she has already nailed with Girls Aloud? "I wanted to do something that was true to me and to what I would listen to at home," she says.

"As weird as it sounds, I do listen to my own albums. But if I don't listen to them, I can't expect anyone else to."

Such empathy is one of the striking things about Cheryl. Whenever a disappointed contestant cries, she is prone to a weep herself. I ask what she thinks of the X Factor's controversial Irish twins, John and Edward Grimes (they have awful voices but last week won the highest number of public votes; fellow judge Simon Cowell calls them "vile"). I expect Cheryl to tear them to pieces. Hardly. "I feel bad for them because of the booing," she says.

"And their family is in the audience. I couldn't sit there while my brother was being booed. You see their little faces crumple at the end of the show. I think if I was sitting at home I'd pick up the phone and vote for them."

Another outstanding quality is her fierce loyalty — to her husband, her band mates, her fellow Geordies and the X Factor acts she looks after. For that reason, she says she is finding Cowell particularly annoying. "I think what's happened is that, because I won last year with Alexandra [Burke], he feels like he's got to be really competitive this year. He keeps putting my acts down."

There have been moments during this series when he has almost managed to crack her composure. But today's Cheryl Cole — immaculate X Factor judge, successful businesswoman, footballer's wife, popular band mate, solo star, style icon — rarely lets the mask slip. It is hard now to connect her with the mouthy Cheryl Tweedy we first met on Pop Stars.

She has come a long way from the Newcastle council estate where she grew up. Flawless grooming and a megawatt smile have replaced tracksuit bottoms and goofy teeth. Her style now is all elegance and class; far behind her are the gritty days of 2003, when she was accused of abusing a lavatory attendant in a Guildford nightclub. She has largely been the victim, rather than the perpetrator, in what little tabloid scandal has surrounded her glossy new persona.

Delightful individual

While Ashley has got drunk and embroiled in grim encounters with ladies who kiss and tell, Cheryl remains poised, down to earth and delightful — at least in our perception, which is all that counts. Unlike other tabloid fodder, she doesn't do stumbling pie-eyed out of nightclubs, sordid cocaine exposes or highly publicised plastic surgery.

Of course, the time will come when we tire of her perfect package; someone else's charm will claim the hearts of the British public. She knows this as well as anybody: "You can't help thinking, ‘When is it all going to stop? When is it all going to go bad?'"

Even I don't envisage her having the staying power of a Madonna or a Kylie, although I'd gladly be proved wrong. Either way, Mrs Cole should make sure that she is having a blast, because it can't get much better than this.