She is one of the country's best-loved agony aunts, who has been solving other people's problems for decades.

But Claire Rayner's warm and positive personality masks the traumas she has endured in her own life. Her childhood was a catalogue of abuse and neglect.

Born in poverty-stricken east London, the young Claire was buried alive for 28 hours in rubble during the Second World War, an evacuee who ran away from four separate families, a nurse aged 14 and made by her feckless parents to leave her first two jobs.

Forced to emigrate with her family to Canada, she developed an overactive thyroid and spent more than a year in a Canadian psychiatric hospital because no one would pay for a thyroid operation.

Deported back to Britain - officially insane and never to see her parents again - Rayner went back to nursing and started to train as a doctor, before meeting her husband Des.

Then she overcame fertility problems and depression to have three children, and rose to prominence as an agony aunt, campaigner and writer.

Now aged 72, Rayner has always refused to tell her own story, until her family and a double mastectomy following a diagnosis of breast cancer in 2001 helped change her mind.

"It'd be an awful thing to make your mind up and never, never change," she says. "You should never be one of those who make up their mind and staunchly never budge, because that's not being clever, that's being stubborn."

But cataloguing her own past was far from enjoyable. "I can't pretend it was," she says. "Digging into the past is like pulling scabs off wounds just to watch them bleed all over again. Who needs it?"

As straight forward and down-to-earth as her advice over the decades, Rayner seems unchanged since her agony aunt prime of the seventies and eighties, apart from her age - evident in her two digital hearing aids, a walking stick she needs because of problems with her fourth artificial knee, and various health troubles, including the double mastectomy, which she dismisses with an "I'd had them a long time, they were nothing special".

Overall, Rayner reflects, hers has been a happy life: "The first 20 years of my life were grotty in the extreme," she says, "and the rest was absolutely bliss. I've no complaints to make, 50 good years against 20 bad. It's a fair deal."

How Did I Get Here From There? by Claire Rayner is published by Virago, priced £17.99 and is available now.