'Definitive' Thatcher biography planned: Author promises new insights on life and career. Marianne Macdonald reports

A biography of Margaret Thatcher which explores her relationship with her mother, her involvement in her son's business affairs and the transformation in her personality after she became Prime Minister has been commissioned by the publisher Jonathan Cape.

This week the biographer, John Campbell, 47, is to sign a contract believed to offer pounds 100,000 over three years in an advance for the book. The 500-page biography is scheduled for publication in 1998.

Dan Franklin, Cape's publishing director, said yesterday: 'The last major biography on Thatcher was by Hugo Young (of the Guardian, published in 1989) which was making polemical points. This will be much more for the record, a definitive book of what happened.'

Dr Campbell was author of Edward Heath: A Biography, for which he won this year's NCR non-fiction prize, and relishes the irony that he is to write in succession about two political antagonists who were consecutive leaders of the Tory party. The Edinburgh- educated biographer's previous subjects have included Lord Jenkins, first leader of the SDP, and the Labour politician Aneurin Bevan.

Baroness Thatcher has refused to be interviewed for the forthcoming biography, which its publishers say will be 'the most definitive until the official papers are released in 2010'. In a letter this month to Dr Campbell, who lives in Notting Hill, west London, she explained that her publishing contract for her memoirs did not permit her to talk but that her office would be prepared to help with 'directions towards published sources'. She has not offered access to any private papers.

Dr Campbell, who describes himself as a Liberal Democrat, hopes to interview Lady Thatcher's Cabinet colleagues and also to search out the second-rank politicians and civil servants from the period who are unlikely to write their memoirs. He also promises to unearth material in America which throws light on the Reagan-Thatcher relationship.

He plans to research her relationship - both financial and personal - with her son Mark, who made his fortune during her premiership, and her mother, Beatrice. Lady Thatcher makes no mention of her mother in her Who's Who entry - describing herself as daughter of 'the late Alfred Roberts, Grantham, Lincs'.

The biographer believes one of the most interesting aspects of Lady Thatcher's career is how unremarkable it was before 1975, when she became party leader. 'I'd like to get into the period when she was Secretary of State for Education under Heath. The fascinating thing is that no one really saw her coming. She was seen as a very ordinary, conscientious, middle-ranking minister,' Dr Campbell says.

'Under Heath, no one saw her as a future leader and I don't think she did herself. The interest is in the way she changed personality so much after she gained power.'

To do so, she transformed herself and was transformed, he says. She lent herself to a repackaging process which altered her hair, clothes, voice and teeth, and developed a belief in her own omnipotence.

Since she lost power, however, the biographer believes she has become a rather sad figure. 'She doesn't know what to do with herself, and is flying round the world like the Wandering Jew looking for audiences that want to listen to her speeches.'

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