LONDON -- As divided Britons sought to define Margaret Thatcher's contentious and transformative legacy, Prime Minister David Cameron lauded her on Wednesday as a woman who had broken through Britain's glass ceiling from her beginnings as the daughter of a greengrocer to make Britain "great again."
Mr. Cameron was speaking at the start of what was likely to be a protracted debate in Parliament to commemorate Mrs. Thatcher, who died on Monday at the age of 87 and is widely seen as one of the most abrasive and influential figures of modern British history.
As much as the verbal tribute, the debate reflected the long reach of her radical policies, which reshaped Britain in the 1980s. In Parliament, even her ideological adversaries acknowledged her stature on Wednesday despite the fact that her free-market policies on labor unions, taxation and the economy divided the land and provoked strikes and riots.
At the same time, her staunchest supporters, like Mr. Cameron, acknowledged that her role as a "conviction politician" meant that "her political story was a perpetual battle" in the country, within Parliament and sometimes within her own cabinet.
The measure of her legacy, he said, is that "so many of the principles that Lady Thatcher fought for are now part of the accepted political landscape in our country."
Mr. Cameron pointed out that she was Britain's first female prime minister and that her 11-year tenure, from 1979 to 1990, was the longest among British prime ministers in over 150 years.
"They say, 'Cometh the hour, cometh the man,' " Mr. Cameron said. "Well, in 1979, came the hour and came the lady. She made the political weather, she made history, and -- let this be her epitaph -- she made our country great again."
"At a time when it was difficult for a woman to enter Parliament, almost inconceivable that one could lead the Conservative Party, and by her own reckoning virtually impossible that a woman could become prime minister, she did all three," he said.
Ed Miliband, the leader of the Labour opposition, recalled Mrs. Thatcher's attacks on the mining industry at home and, abroad, her condemnation of Nelson Mandela's African National Congress as a "terrorist" organization.
Mrs. Thatcher's critics accuse her of being on the wrong side of history in South Africa, seeming to support the apartheid government in its bloody confrontation with protesters in the 1980s and opposing economic sanctions meant to weaken white rule. But some in South Africa say she contributed to Mr. Mandela's release from prison in 1990 after 27 years of incarceration.
"She had a much better grasp of the complexities and geostrategic realities of South Africa than many of her contemporaries," F.W. de Klerk, the country's last white president, said in a statement issued in South Africa.
Mr. Miliband, seeking to strike a balance between offering respect and maintaining ideological distance, told Parliament that while Mrs. Thatcher was a "unique and towering figure," she "made the wrong judgment about Nelson Mandela and sanctions in South Africa."
"I disagreed with much of what she did," Mr. Miliband said, "but I respect what her death means for many, many people who admired her and I honor her personal achievements."
He went on: "it would be dishonest and not in keeping with the principles Margaret Thatcher stood for, even on this day, not to be open about the strong opinions and deep divisions there were and are."
The parliamentary session was unusual in two senses -- both the upper House of Lords and the lower House of Commons had been recalled from recess and the time set aside for tributes was more than seven hours, compared with the 63 minutes devoted to another former prime minister, Edward Heath, after his death in 2005.
Mr. Cameron, like many Conservatives, casts himself as a political heir to Mrs. Thatcher, the Iron Lady whose ascendancy ended when the same party that is now praising her pushed her from office, to be replaced by John Major.
The Thatcher era is generally recalled as a time when a capitalist revolution crushed labor unions, decimated staid industries that had once formed the nation's economic base, and inaugurated a period of robust economic growth that sanctified a generation's acquisitiveness.
The parliamentary debate on Wednesday came a week before Mrs. Thatcher's ceremonial funeral, to be held under tight security precautions in central London. It presented a particular challenge to Mr. Miliband, because some of his followers believe that more than any other postwar leader, Mrs. Thatcher caused distress and hardship for hundreds of thousands of blue-collar Britons as she broke the power of once-mighty mining, print and other unions.
Such are the passions stirred by her legacy that some opposition lawmakers said they would boycott the session.
John Healey, a former government minister from the Labour party, said Mr. Cameron had sought to use Parliament for his own political purposes. "He's wrong to recall Parliament, and wrong to hijack it in this way," he said. "I will play no part and I will stay away."
Some lawmakers have also challenged the cost and appropriateness of a funeral similar in pomp and solemnity to those of Diana, Princess of Wales, in 1997, and the Queen Mother in 2005. Her body will be borne on a gun carriage to St. Paul's Cathedral for the service, to be attended by Queen Elizabeth II, among many others.
British news reports said there was speculation that guests would include Mikhail S. Gorbachev, the former Soviet leader, and Nancy Reagan, the former American first lady. Given her disputed legacy, security arrangements are expected to be similar to those for the 2012 London Olympics, the news reports said. About 700 military personnel will be part of the occasion.
Mark Thatcher, Mrs. Thatcher's son, said in a statement outside her London home on Wednesday that her family was "enormously proud and grateful" that the queen would attend. "And I know my mother would be greatly honored as well as humbled by her presence," he said.
Two former Labour prime ministers, Tony Blair and Gordon Brown, plan to attend the funeral next week, British news reports said.
Partisan sniping, though, underscored the depth of division about her legacy. The Conservative foreign secretary, William Hague, told BBC television that the biggest problem for the British left was that "they could never beat her" at the ballot box in her three terms in office.
And some figures in the Church of England questioned whether the tone of the funeral service would match the church's opposition to some of Mrs. Thatcher's policies.
Giles Fraser, a former senior cleric at St. Paul's Cathedral, said the Anglican Church was often the "unofficial opposition" to Mrs. Thatcher.
"Every day in that cathedral, the choir will sing about Jesus, that he brought down the mighty from their thrones then lifted up the lowly, filled the hungry with good things and sent the rich away empty," he said in a radio interview. "They are very strong words. They are not words that you would necessarily associate with Mrs. Thatcher. This is a problem."
John F. Burns reported from London and Alan Cowell from Paris.
This article originally appeared in The New York Times.