A friend of mine can pinpoint the exact moment at which he grew up to an encounter in a Casablancan bar 31 years ago. He was attempting to chat up a gorgeous fellow traveller with tales of his wild and crazy adventures. He thought he was the original trailblazer and, as such, that girls, no matter how gorgeous, would be captivated by his fascinating life and long hair. This girl wasn’t. She listened for as long as it took for him to reach the end of his interminable tale, then turned to him and said, “Why are you swearing so much? Is it because you think it makes you sound grown up?” She then vanished, taking my friend’s ego with her.

Charlotte Church hasn’t had such an epiphany yet. She hasn’t worked out that gratuitous swearing doesn’t make you cool. In fact, she sees it as a sign of maturity. When fragile fans from her Pie Jesu days wrote disgusted-from-Tunbridge-Wells letters expressing their shock at her coming-of-age foul mouth, her response was simply: “What can I say? I’m sorry but I grew up?”

Perhaps by the time she co-writes her third autobiography (incredibly, this is her second), she will have mastered her mouth. Because as every grown-up knows, swearing should be used only in extremis. Which brings me to an early verdict on Keep Smiling: it’s ****.

We all know the story: child star with voice of angel signs 1,000-year contract with big record company, tours world promoting perpetually Christ-massy albums, loves celebrity, tires of celebrity, rebels, smokes fags, dates yob, rein-vents self as foul-mouthed pop-star/presenter, settles down with Welsh rugby player, the end. So, if we all know it, why should we be subjected to 320 pages about it?

Ah silly, to see the real Charlotte Church, not the binge-drinking, fallen-angel tabloid version. But having just waded through those 320 pages, I’m none the wiser. Or rather, I was wise enough in the first place, thank you very much. “I remember once, when I was throwing up outside RSVP, Abi came out, looked at it and suddenly projectile vomited. Astonished, we looked at each other and burst out laughing before going back in and carrying on dancing. We were nuts and I loved every second of it.” Turns out she isthe binge-drinking fallen angel they said she was: it’s just that in an autobiography this isn’t remotely interesting. Because you’re not really nuts if you throw up outside a nightclub, are you? You’re just a teenager.

The first few chapters are devoted to the tiny bit of life when Charlotte wasn’t famous. The high-light, apart from a long passage on what she used to have in her packed lunch, is the revelation that she killed a goldfish she won at a fete. “I wanted to see what would happen if I squeezed him,” she writes, “so I did . . . hard . . . until blood oozed out of his gills.” (I put a wasp in a microwave once, but I don’t think I’d bother putting that in my autobiography.) Then, at the age of 11, she’s spotted on a talent show, her debut album goes platinum and the whole thing becomes a series of depressing recollections: an 11-year-old and her star-struck family struggling to eat pheasant at a Vatican banquet, a manager taking a huge cut of the first record deal, having her eyes stretched for a Japanese television ad, and George Bush asking what state Wales is in.

After that initial surge, we are subjected to a Chinese water torture of repetition. Each time another album comes out, there’s a forensic name-checking of music-industry insiders none of us cares about, interspersed with the slagging of fellow slebs for the Grazia generation and a slice or two of personal trauma because that’s what you have to do in an autobiography. Chuck in a riff on how annoying parents are and it’s like reading a teenager’s diary, only instead of bibble about Johnny from the boy’s school and that slag Susie, it’s about Shirley Bassey, Robbie Williams and Christina Aguilera. Which, in the cold light of book print, isn’t any more interesting, I promise you.

Let’s wait until she’s 40, survived crystal-meth addiction, become Welsh prime minister and discovered a cure for baldness before we are subjected to the third instalment. Please.

PS: I hate to give the plot away, but she had Wagon Wheels in her lunch box.

KEEP SMILING by Charlotte Church
Orion £18.99 pp320
Buy the book here at the offer price of £17.09 (inc p&p)

Times Recommends

• 10 things you should avoid in hospital (unless there really is no option)
• Exclusive: Philip Pullman's essential reading list
• The White War by Mark Thompson