At 20 the tabloids were gleefully reporting that Billie Piper was washed up. But winning turns in a Shakespeare adaptation won her the coveted role of sidekick to Doctor Who number nine and, as Katherine MacAlister discovered, she hasn't looked back since.

At just 23, it may seem arrogant to produce your autobiography, but then Billie Piper has already done more living than Doctor Who's had episodes.

And Billie is the first to apologise for this. "It may sound ridiculous being just 23, but I've a few a good stories I'd like to share. I'm hoping the book will be honest, funny, insightful and, above all, life-affirming.

"This is a chance for me to talk openly about other areas of my life, things that I'm hoping lots of people can relate to and maybe even be inspired by."

Bypassing her childhood completely in favour of a life under the spotlights, the pop princess had her first number one Because We Want To aged 15 and six more hit singles in the next three years. Add to this a nervous breakdown, battle with anorexia, Vegas wedding and relaunch as an award-winning actress, and you soon realise why Growing Pains is such a page-turner.

One subject that remained unbroached until now was her marriage to Chris Evans. She also discusses the rift with her parents, the truth behind those tabloid drug allegations, her gradual recovery and success as a bona fide actress.

Billie Piper is back and this time around she knows where she's at, because while to the outside world her life seemed a glamourous whirlwind of showbiz, famous lovers, fame and money, the reality was shockingly different.

Behind that famous smile was a bewildered teenager, cut off from her friends and family in Swindon, hiding her anorexia from a prying world.

"The press were wrong about drugs. It wasn't drugs that were ruining my life, but a good old-fashioned eating disorder."

Brought about by a rigorous schedule that would have flummoxed Margaret Thatcher, Billie protested by starving herself to bring some small modicum of control into a life dictated by her record company and the media.

When she had signed on the dotted line of her million-pound record contract, it was all she had ever aspired to, but by the end she felt trapped, old and burnt-out.

"I didn't want any of it any more, but I couldn't get out of it. I had started the whole thing, but there was no way out - I think that's why the walls closed in on me."

A student at the famous Sylvia Young Theatre School in London, Billie got to the top through sheer hard graft, and her work ethic never diminished however much they asked of her.

"I was not really being parented at all. And because my real parents thought that someone else was doing the job, I slightly fell between two stools," she remembers.

Failed suicide attempts, public collapsing through lack of food and sleep, even hospitalisation were all symptoms, so falling in love with Chris Evans was the best thing that could have happened to her.

Yes, they met on TFI Friday, yes he wooed her with a Ferrari before she could drive and yes they got married in Vegas when she was 18 and he was 34, but in private Chris Evans let Billie take the time out she so desperately needed.

She set up home, learned to cook, read, travelled the world, slept, laughed and relaxed. And, for a while, the Evanses were blissfully happy.

Winning the part as Rose in the new Doctor Who series was the beginning of the end for them. Her success took them both by surprise and the couple, who had been inseparable, were forced to spend long periods of time apart.

"He slowly - maybe to protect himself, maybe not - started to let go of me and in the process let me fly away."

Now separated, Billie has nothing but praise for Chris.

Or as Billie put it: "Chris was my Doctor Who. But I was fixed now and it was time to stand on my own two feet. I returned to my world a stronger, better and more fulfilled person than I'd been before."

Being voted Most Popular Actress at the 2005 National Television Awards and winning The Times Breakthrough Award in 2006, proves this.

Since then Billie has filmed the BBC's big Christmas drama, Oxford author Philip Pullman's The Ruby In The Smoke and is currently filming Mansfield Park for ITV. She is visiting Borders in Oxford at midday on Wednesday.