Thatcher presented her principles as being as immovable as her lacquered, honey-colored hair. She famously spun the title of a postwar play into her signature line about staying the course: "The lady's not for turning."
Her capacity for hard work and little sleep was legendary. In 1984, three years after she refused to concede to imprisoned Irish Republican Army hunger strikers, 10 of whom died, the IRA bombed a Conservative Party convention in the seaside town of Brighton. The blast, which occurred shortly before 3 a.m., ripped through Thatcher's hotel bathroom, but she was still awake and working on her speech in another room.
The attack killed five of her Tory colleagues. Thatcher insisted that the conference go on.
"She was very macho," Sir Bernard Ingham, her longtime press secretary, told The Times. "She was absolutely determined to demonstrate that she could beat the men."
In outlook, gender and class, she was almost as different from many of her fellow Tories as from the opposition Labor Party. Her brisk, assured style rattled the ramparts of the upper-class, Oxbridge-educated, "toffee-nosed" segment of the Conservative establishment, which looked down on the striving middle class from which Thatcher arose.
She was born Oct. 13, 1925, to Beatrice and Alfred Roberts. Her father was a shopkeeper and also the local mayor, rigid in his thrift and moral principles, a reader of Kipling and conservative newspapers.
"I owe almost everything to my father," Thatcher said, and that included her politics and ambitions.
She won a place at Somerville College, Oxford University, and studied chemistry under future Nobel laureate Dorothy Hodgkin. A short career in science saw her work at a firm that made plastics and another that tested cake fillings, and she was a member of the team that developed soft-serve ice cream.
But politics and Parliament were far more fascinating than test tubes. In 1959, she was elected to the House of Commons, its youngest female member, and swiftly rose in the Conservative ranks. By then, she had married Denis Thatcher, a rich, divorced businessman. They had twins, Carol and Mark, two years later in 1953.
Thatcher was appointed secretary of state for education in 1970, and five years later was elected leader of the Tories, who were then out of power.
She became prime minister in May 1979 when voters booted Labor from power after Britain's "winter of discontent," during which a series of strikes left bodies lying unburied in mortuaries and mountains of garbage lying uncollected in the street.
Almost immediately, Thatcher slashed income taxes but raised them on goods and services, a move criticized as shifting the burden down the income ladder.
Some of her fellow Tories were as disgusted as the Labor Party; their old-school noblesse-oblige policies parted company with Thatcher's more Darwinian politics. And women who had hoped she would be a feminist beacon were also disappointed when Thatcher brought precious few women into her government.
But she knew how to use her gender to good effect.
"I used to say she was absolutely set in her ideology and in her conviction because a man couldn't get at her in the Gents" -- the men's bathroom, said Ingham.
Her husband's support was complete and unwavering, and she returned the favor. One evening, when Thatcher was still a Cabinet member, she hurried out of the office to buy bacon for her husband's breakfast. When her boss told her there were plenty of people who would be glad to do it for her, she said only she knew how to do it right.
She was conscious of her image, up-marketing her looks and taking elocution lessons to bring down her shrill tones to what the Daily Telegraph called a "fruity contralto."
She was not consistently socially conservative; she voted to legalize abortion at the same time that she supported capital punishment.
But she was often brutal and belittling toward her own political allies, a propensity that eventually helped lead to her downfall. During one crisis, minister Michael Heseltine stalked out of a Cabinet meeting after shouting at Thatcher: "I hate you, I hate you!"