Margaret Thatcher

London (CNN) -- Former British Prime Minister Margaret Thatcher, a towering figure in postwar British and world politics and the only woman to become British prime minister, has died at the age of 87.

She suffered a stroke Monday, her spokeswoman said. A British government source said she died at the Ritz Hotel in London.

Thatcher's funeral will be at St. Paul's Cathedral, with full military honors, followed by a private cremation, the British prime minister's office announced.

Thatcher served from 1975 to 1990 as leader of the Conservative Party. She was called the "Iron Lady" for her personal and political toughness.

Thatcher won the nation's top job only six years after declaring in a television interview, "I don't think there will be a woman prime minister in my lifetime."

During her time at the helm of the British government, she emphasized moral absolutism, nationalism, and the rights of the individual versus those of the state -- famously declaring "There is no such thing as society" in 1987.

Nicknamed the "Iron Lady" by the Soviet press after a 1976 speech declaring that "the Russians are bent on world dominance," Thatcher later enjoyed a close working relationship with U.S. President Reagan, with whom she shared similar conservative views.

But the British cold warrior played a key role in ending the conflict by giving her stamp of approval to Soviet Communist reformer Mikhail Gorbachev shortly before he came to power.

Thatcher -- born in October 1925 in the small eastern England market town of Grantham -- came from a modest background, taking pride in being known as a grocer's daughter. She studied chemistry at Oxford, but was involved in politics from a young age, giving her first political speech at 20, according to her official biography.

She was elected leader of the Conservative Party in 1975, when the party was in opposition.

She made history four years later, becoming prime minister when the Conservatives won the elections of 1979, the first of three election victories to which she led her party.

As British leader, Thatcher took a firm stance with the European Community -- the forerunner of the European Union -- demanding a rebate of money London contributed to Brussels.

Her positions on other issues, both domestic and foreign, were just as firm, and in one of her most famous phrases, she declared at a Conservative Party conference that she had no intention of changing her mind.

"To those waiting with bated breath for that favorite media catchphrase, the U-turn, I have only one thing to say: 'You turn if you want to. The lady's not for turning,'" she declared, to cheers from party members.

[CNN video]