By Ollie Stone-Lee
BBC News political reporter
Margaret Thatcher has one historical achievement which not even her fiercest enemies can dispute: she was Britain's first woman prime minister.
How much of a trailblazer for women was Mrs Thatcher?
She did it too in a Conservative Party which would not allow her, or other women, to become member of that Tory bastion the Carlton Club.
And it was at a time when there were only 27 female MPs (by the time she left Downing Street in 1990 there were 43).
There appears to be consensus from friend and foe alike that Thatcher made into Downing Street in spite of being a woman, not because of it.
Shirley Williams, who crossed swords with Thatcher when she was a Labour Cabinet minister in the 1970s, says: "She did very little by being a woman, she did it by being herself."
But she says it was an amazing achievement to become the first female prime minister, especially when she had not come from a privileged background.
Baroness Williams says: "She had this extraordinary power of the will: single minded, with a clear objective and it was not to be the first woman prime minister. It was quite straight-forwardly to be leader of the Conservative Party."
That was particularly because Mrs Thatcher was so determined to beat Ted Heath in the 1975 Conservative leadership election.
Lady Williams touches on a paradox which many believe lies at the heart of Thatcher's status as first female prime minister: her influence on the campaign for greater equality for women.
"She did not got out of her way to help women," she says.
There was only one other female Cabinet minister during the Thatcher years in Downing Street, with talented figures such as Lynda Chalker left languishing in lesser posts.
It is a point which angers ex-Tory ministers such as Edwina Currie.
And Patricia Hewitt, a minister Tony Blair's Cabinet, told the BBC News website: "Margaret Thatcher broke through the glass ceiling in politics. But it is a tragedy that, having become the UK's first women prime minister, she did so much to undermine the position of women in society.
"Margaret Thatcher damaged women's place in the workplace, undermined families and communities, and did nothing for women in public life. It was a wasted opportunity on a gargantuan scale."
Lady Williams says Thatcher's rise changed attitudes
But the mere fact that Mrs Thatcher was a woman and reached the peak of political power had an impact.
Lady Williams says: "Her own achievement of course changed the whole attitude of people to what women could achieve but it was very much a personal achievement...
"She didn't see herself as a leader of the women's movement but little girls begin to think they could be prime minister."
Julie Kirkbride, now a Conservative MP, was one of those schoolgirls when Thatcher became Tory leader in 1975.
She says it was Thatcher's beliefs, not her gender, which inspired her to join the Conservative cause.
But she went on: "She has demonstrated that if you are the right person and are the best, there is no glass ceiling."
Ms Kirkbride says there were questions at the time about whether Mrs Thatcher as a woman would be strong enough - in fact she became Britain's most steadfast post-war prime minister.
Although Mrs Thatcher was selected to fight Dartford in 1950, she was turned down for several winnable seats, despite her evident talents, before being selected in 1958 to contest Finchley, where she was elected the next year to Parliament.
Lady Williams believes Mrs Thatcher was at least helped by having a husband who was a wealthy businessman.
Only once did Lady Williams ever talk to Mrs Thatcher about being a woman in a male-dominated Parliament, albeit obliquely.
Then a Labour minister, Williams had just undergone a particularly hostile Commons questions session.
Thatcher told her: "We have to show them that we are better than them."
The late Hugo Young suggested in his acclaimed Thatcher biography, her attitude to the cause of women changed during her career.
In 1952, she wrote in the Sunday Graphic that women should not feel a duty to stay at home.
"Should a woman arise equal to the task, I say let her have an equal chance with the men for leading Cabinet posts. Why not a woman chancellor? Or foreign secretary?"
But Young said her views were different once she had reached the top. In a 1982 lecture she said: "The battle for women's rights has largely been won.
"The days when they were demanded and discussed in strident tones should be gone forever. I hate those strident tones we hear from some Women's Libbers."
Lord Bell, Thatcher's advertising adviser, says her constant femininity" shined in the way she dealt with issues.
"She also I think sometimes used it to her advantage when it suited her," he said.
"She was in a world dominated by men and one of the things men are very bad at is handling women."