The world premiere of Kylie Minogue’s White Diamond - “An intimate portrait of Kylie Minogue” – and around 1000 people line the red carpet at Leicester Square, waiting for her arrival. The crowd includes two drag queens, wearing gigantic pink and white ostrich feather head-dresses, which slowly turn into damp rats tails in the rain outside Burger King.

Even in the rain, however, they are still more glamourous than celebrity guest Rupert Everett, who turns up in a greasy pair of tracksuit bottoms and three inches of stubble, looking as if his taxi was booked to pick him up from a bin. Next to Kylie – arriving to screams and cheers and luminous in, of course, white diamonds – he looks like a tramp. He looks puzzlingly, fundamentally unsuited to the dazzle and sequin of a Kylie Minogue event.

Filmed between August 2006 and March 2007, White Diamond follows Kylie on her resurrected “Showgirl” tour – originally abandoned halfway through, in Sydney, when she was diagnosed with breast-cancer. White Diamond aims to show her “Home coming” – the reactivation of the Showgirl tour, which was reworked to be “Light, joyful and fun, as always; but that means something much deeper, now given the context,” as choreographer Akram Khan explains.

Over the course of two hours, we see Kylie in private jets, on the beach, in the dressing room, working on designing a leopard cat-suit with Dolce & Gabbana, singing with sister Dannii and – of course – looking totally, totally fabulous. This rolling-news access is due to the film being the work of Will Baker – Kylie’s key-note stylist, photographer and collaborator-cum “gay husband”, as she puts it. Their relationship is endearingly close – they refer to each other, constantly, as “dear”, like a elderly couple sunning their knees on a beach at Clacton seafront.

However, the main problem with White Diamond is, perhaps, that Baker is too close to his subject. During an arse-fatiguing two hours, White Diamond follows Minogue during a triumphal home-coming gig, a post-stage collapse due to respiritory tract infection, New Year’s Eve at Wembley Arena, and the break-up of her long term relationship with the actor Olivier Martinez - but we never see Minogue cry.

Likewise, we never see her shout, or bitch, or get tipsy, or maudlin. She comes across as resolutely sunny, stoic and giggly – which, by all accounts, she actually is - but anything even remotely resembling a newsworthy moment has clearly been exorcised by either Baker, or Minogue herself.

“For most people, Neighbours, Michael Hutchence, gold hot pants and cancer = Kylie,” Baker suggests to his star, right at the beginning. “I want to rip that surface away.”

Alas, over the next two hours, Baker doesn’t so much rip the surface away as gently caress the surface, going “Mmm, lovely surface”. White Diamonds reveals far less of Kylie Minogue than the legendary hot pants did. To be honest, it reveals less than a well-cut winter coat and knee-boots would.

If the censorship is on Baker’s half – which I rather suspect it is – then this is surely the action of a friend who knows, first-hand, how the tiniest salient detail of Minogue’s life can become tabloid and magazine fodder for weeks, and who wishes to spare her from further papping and scruntiny. And this is, clearly, why he is a good friend, and is allowed to sit in Kylie’s dressing room while she dances around in her pants, which is what everyone in the world wants to do, really, if they’re honest. The one thing White Diamonds leaves you in no doubt about is that Kylie Minogue is a charming, merry, adorable disco mouse with a fabulous collection of shoes.

But ultimately, it does rather leave the viewer wondering why on earth the documentary was actually made. In In Bed With Madonna, Madonna fellates a Coke bottle, calls her dancers “bitches”, slags off Kevin Costner, and shoots red-hot sex-looks at Warren Beatty every ten minutes. In White Diamond, on the other hand, we see Kylie getting in and out of a lot of cars, and giving Will Baker lots of hugs. The over-riding image of the film is of a tired, crop-haired girl napping on sofas in between shows, waiting for her skin to start glowing again, and wearing bright sequins on her eyes until it does.

Of course, there are good bits. Some poor runner, atomiser in hand, spraying plants at a party with Minogue’s perfume, “Darling.” Bono being winningly sardonic about filling Robbie Williams’ spot on a performance of Kids (“How does Robbie do it? He is my inspiration,” before tearing the roof off with his version.) And there’s a running gag of the tour-manager, Sean, having the sole, recurring line “It’s a nightmare”, as computers go down, or backing dancers loose their shoes.

But, ultimately, this is a documentary made by a very discreet friend, about someone very responsible and lovely, on a tour where every day they took the rigging up, and then took it back down again, and everyone was in bed by midnight.

And if that’s not what the tour was like, and that’s not what Kylie is like, we’re none the wiser at the end of two hours.

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