When Ronald Reagan departed this life, Americans joined in an outpouring of bipartisan mourning that ranged from genuine grief to grudging respect for the memory of the Gipper. On this side of the Atlantic, the reaction to the death of his political soul mate, Margaret Thatcher, could not be more different.

Rather than unite Britain, Thatcher’s death appears to be opening old wounds.

Opponents have launched a social-media campaign to promote the “Wizard of Oz” song “Ding-Dong! The Witch is Dead” (No. 10 on the British charts Wednesday), as well as Elvis Costello’s 1989 anthem “Tramp the Dirt Down,” in which he sings of dancing on Thatcher’s grave. The city of Birmingham, a bastion of the working classes, has refused to fly the Union Jack at half-staff. Various groups have pledged protests to coincide with the Iron Lady’s elaborate funeral next week.

In a few blue-collar neighborhoods across Britain, opponents held impromptu street parties to celebrate her death and are planning more to mark her funeral. In the hours after she died, the Telegraph — the leading conservative broadsheet here — was forced to close its online comments section because of a barrage of vitriol posted by Thatcher’s detractors.

Noting the Thatcher years of the 1980s as a time when British progressives and conservatives seemed like two tribes gone to war, Jonathan Freedland, a columnist for the Guardian, wrote, “Strangely, it feels like that again now — two tribes battling over the memory of the fiercest warrior they ever knew.”

A cultural divide

The division here offers telling differences not only between Reagan and Thatcher — larger-than-life conservatives whose legacies are inexorably linked — but also between the United States and Britain, which tend to view their elected leaders in very different ways.

Thatcher and Reagan shared strategic visions of Western military might and an economic philosophy of pulling yourself up by your bootstraps. Yet Thatcher, many argue, was relatively more transformative and thus earned more enemies. Yes, Reagan broke the air-traffic controllers and promoted trickle-down economics. But Thatcher inherited a country of state-run industries, used steely will to bust organized labor and changed the nature of grass-roots politics forever. Rather than fine-tune, her free-market push reinvented the British economy.

And then there were their personalities, with Reagan’s naturally amiable and Thatcher’s hard-edged. Her image as unyielding never really softened even as she, like Reagan, fell into a long struggle with dementia that might have otherwise cultivated empathy from old foes.

“The battles Thatcher fought with the left in Britain were larger, more dramatic, than Reagan’s in the United States,” said James Forsyth, political editor of the magazine the Spectator. “And if you look at how Reagan campaigned, he had a genial side that Thatcher didn’t.”

The across-the-aisle accolades for Reagan upon his death in 2004 were, some argue, one of the last hurrahs of a post- Sept. 11, 2001, bipartisanship that has largely faded in Washington. Yet observers say Americans tend to view their presidents in far more revered terms than the British do their prime ministers. Winston Churchill was and remains a national hero, but it is not in the British tradition to name airports, buildings or even streets after the residents of No. 10 Downing Street. With few exceptions, Britons reserve their reverence for the queen.

For segments of British society, that made the grocer’s daughter who became this nation’s most transformative peacetime prime minister more the head of a Conservative government than a leader of all Britons. Her most divisive political ideals — of austerity and small government, of an end to welfare and an independent role for Britain in Europe — are issues that have again surged to the forefront of the national debate.

James Doleman, 46, a Scottish writer and activist, joined an impromptu party Monday to celebrate Thatcher’s death in Glasgow’s George Square. He said revelers danced in the streets with open bottles of champagne.

“The deep division she caused has been reflected in her death,” he said. “She caused the shipyard to shut down. The economic base of the whole city was ripped apart, and our whole lifestyle and culture went with it. It was annihilated.”

And yet flash polls suggest those Britons cluttering the Twittersphere with cheer at her death represent a vocal minority. An ICM Research poll Monday suggested that 50 percent of respondents viewed Thatcher as a net positive for Britain, compared with 34 percent who saw her as a negative. Her son on Wednesday thanked those who continue to pay tribute.

A deeper debate

Beyond the vitriol, a more thoughtful debate has begun. The rock-and-rollish British comedian Russell Brand, no fan of the late prime minister, wrote a piece Tuesday recalling his recent sighting of Thatcher looking like “a pale phantom” as she “feebly” watered flowers in a park. He suggested the woman who had struck fear and loathing in the hearts of her opponents had actually departed long ago.

“If you opposed Thatcher’s ideas it was likely because of their lack of compassion, which is really just a word for love,” Brand wrote. “If love is something you cherish, it is hard to glean much joy from death, even in one’s enemies.”

On Wednesday, members of Parliament offered up a marathon session to her legacy, with Prime Minister David Cameron, a fellow Conservative, saying, “Let this be her epitaph: She made the country great again.”

Ed Miliband, leader of the opposition Labor Party, said, “She was right to recognize our economy needed to change.” But he added, “It would be dishonest and not in keeping with the principles that Margaret Thatcher stood for, even on this day, not to be open with this house about the strong opinions and the deep divisions there were, and are, over what she did.”

Eliza Mackintosh contributed to this report.