Dannii Minogue has promised to take me Power Plating. Promised. She has also promised to give me the name of a photographer who takes great nude portraits (“Every woman should be photographed nude,” she insists. “It’s so liberating”); to give me the recipe for her special feta and watermelon salad (“Usually I hate fruit in savoury, but this works’); and to tell me who is the best person in London for Botox. “The one who does Simon’s,” she confides, “he’s a little, er, ag-griss-ive.” Not that she herself has it done any more, as you would know if you were one of the millions who saw her being interviewed by Piers Morgan the other night. “See?” she says, lifting up her little cow’s lick of a fringe and energetically moving her brows up and down. “Lines!”

How time flies. And how things change. This time last year, it was all about Cheryl. Now it’s all about Dannii. Where once it was the trend actively to dislike her, poor girl, to wonder what on earth it was that Simon Cowell saw in her — couldn’t he afford her sister, sort of thing? — now, well, we can’t seem to get enough of her. Is it the relaxing on the Botox front? Is it the love of a good (cute) man? Has that old maternal instinct finally kicked in? (She says it’s her boyfriend, Kris Smith, a rugby player and model, who’s all “clucky”, not her; she’s terrified about what pregnancy will do to her body, but still.) Who knows, but the new improved Dannii, with her new little bob and her new moving brow, she’s sure giving Cheryl one helluva run for her money. And America — finally, finally, it’s calling, as it has already rather gallingly done for Cheryl and Cat Deeley. Ugly Betty and Desperate Housewives. These are only two of the shows that are on the cards.

“Well, I’m putting it in the mix. I feel I’m in a position to do that now,” she says carefully. “It’s weird to be objective anyway, but I think everyone has their 15 minutes of fame. And maybe, who knows, this is mine.”

It is midmorning and we are sitting in a suite at the Metropolitan hotel drinking “groin tea”. Although the grey morning light could not be more unforgiving, Dannii’s skin is as porcelain perfect as it is on screen. As for that pocket-rocket body — swathed today in grey Donna Karan — TV simply doesn’t do it justice. People can be unkind about all the work she has had done, Graham Norton can call her a “spoon with hair”, Sharon Osbourne can liken her to a mosquito that wouldn’t go away, but gosh, is she pretty. No, beautiful, with that perfect rosebud smile and those glassy china-blue eyes. Horst, Beaton — would that they were alive to capture it. But then, so she always has been, even in the plump punk days back in the 1980s, when she’d sit on the TV-am couch and gracelessly answer questions about her more famous sister.

As she might be doing now, frankly, had The X Factor not come along. “Yup, I always tell Simon, if he only knows the chance he gave me,” she says, delicately placing one grey YSL Tribute over the other (the lace Louboutins Cheryl gave her for her birthday are still in their box “being worshipped”). The X Factor and Australia’s Got Talent (she’s flying off to Melbourne as soon as one show finishes here to start filming the other there) are, Dannii gratefully admits, what have helped her turn the corner after those bleak times when her sister had been diagnosed with cancer and her best friend died of the same disease.

Oh God, the show’s been rough at times: Sharon Osbourne behaving like an alley cat, everyone constantly pitting her against Cheryl, and then, most recently, being moved below the salt to the end of the judges’ table. What does she feel about that? “Look, last year it was really, really bad,” shrugs Dannii. “I felt out of control. The only thing that could anchor me through all that Sharon stuff was Simon. This year, well, I keep having to accept it’s all pantomime. I’m being given a role rather than being myself and having an opinion. People want me to turn into a Sharon, but that’s never going to happen, so keep those comments coming. It’s good for the show!’

Ah, the show. Of course, everybody is watching it this year (it hit 14.7m two weeks ago) and we are all gripped. “But do you watch it? You do? Who do your kids like?” Jedward, I tell her. “They do? We thought that was people coming out of the pubs, who were drunk, who voted for them, but it really is the kids, too.” So tell us more, Dannii. What about Lucy? “I think the reason Simon was so mean to her that time was because he fancied her.” And what about Danylgate? “Me? Homophobic? It can’t be! I mean, do they know the meaning of the word Minogue?”

Everyone wants to know what Dannii is like in real life. Well, I’d be lying if I said she radiates hot-water-bottle cosiness. But she can be girly, she can be real, if she works it. Yes, there is something cipher-like about her in the flesh, but having been a child star since the age of nine back in Australia (where she was way more famous than Kylie), one cannot really blame her.

That lack of animation, those wooden reactions (not to mention the accusations that those televised tears for Piers Morgan were a tiny bit crocodile) that have a habit of carrying over to real life, might be less about the Botox and more about creating a protective shield around herself, the way that former child stars who’ve never had the chance to be civilians often do.

“Look,” she says in her flat, careful way, “it wasn’t about crying or not crying, it was just the chance to tell my story, my way, in my time. I knew the subjects were going to be ones that were really confronting. In front of the camera or in private — they make me shake. I tried to compose myself as much as I could. In 30 years of work, I’ve only ever cried twice on TV.” (The other time was when Louis accused her of stealing one of his songs.)

To keep that empathy muscle activated — and why not, if it works? — she has been engaging in a little self-discovery. Not therapy — “I have my sister for that,” she says briskly — but in reading around the subjects of spirituality and other people’s hardship. Elizabeth Gilbert’s Eat, Pray, Love made a huge impression, as did John Boyne’s The Boy in the Striped Pyjamas. She is very attracted to the Jewish religion, she says, frequently joining in her friends’ Shabbat celebrations, and believes it very important to keep things in the present. “Though sometimes I feel I ought to have a yellow Post-it note on my forehead to remind me!” she says with a good ol’ Aussie cackle.

Oh, but what about these ludicrously good-looking men she keeps aligning herself with? Will she ever transcend that? Her ex-husband, the Nip/Tuck actor Julian McMahon, is a former Levi’s model. As for her current beau, whom she met at a club in Ibiza... Well, I mean, look at him. “Oh I know,” she says fondly, showing me a picture on her BlackBerry of him in his pants taken by the guy who does all the Dolce & Gabbana underwear ads. “To be honest, he’s not my type at all. I never go for guys who are as blatantly attractive as that. But Kris, well [little sigh], he’s different. These northern boys, we need to import a few to London.”

Dannii has kept her promise. We join each other for a session of Power Plating on the fifth floor of Harrods. Looking even more delicate and doll-like with her hair scraped back in a silver alice band, no make-up whatsoever and flip-flops, she has brought with her a little bag of things for me. A jar of the coffee substitute she buys in bulk before going back to Australia (because the real stuff makes her shaky) and a handmade blend of oils I’m supposed to shove under my nose to stop me from getting tired. The Botox thing? Hmm, she’s really not sure she should recommend that to anyone. A nudie photo shoot with her brilliant friend Elizabeth Hoff, that would be a much better “lift”. As for Power Plating, wait till I see how it pushes everything up, just wait.

Dannii Minogue with a yellow Post-it note stuck to her forehead reading Be Present. The cover for a bestselling autobiography, or what?

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