A painting in Dyrham House, a grand mansion in southwest England, offers a panoramic view of the port of Bridgetown, Barbados, with sugar plantations dotted along a hillside.

In another room are two carved figures depicting kneeling Black men, holding scallop shells overhead. They are chained at the ankles and neck.

These works belonged to William Blathwayt, who owned Dyrham in the late 17th and early 18th centuries, and, as Britain’s auditor general of plantation revenues, oversaw the profits that rolled in from the colonies.

Explaining the history of a place like Dyrham can be contentious, as the National Trust, the nearly 130-year-old charity that manages many of Britain’s prized historic homes, has found out.

After the organization revamped its displays to highlight the links between dozens of its properties and the exploitation and slavery of the colonial era, it drew the wrath of some right-wing columnists and academics, who accused the trust of being “woke,” suggested that it was presenting an “anti-British” view of history, and began a campaign to roll back some of the changes.

The ensuing battle — which has echoes of the heated debate over Confederate monuments in the United States — has played out for three years on social media and in right-wing newspapers in Britain.

So far, the National Trust has resisted the campaign and has stood by its new displays and their references to colonialism and slavery. But the controversy has roiled the trust, whose annual meetings have seen an opaquely funded group, Restore Trust, try to put its candidates on the charity’s council, an advisory group that works with the trust’s governing board.

‘Modish, Divisive Ideologies’

The National Trust was established in 1895 to preserve natural and historic places. It has spent 129 years acquiring stately homes, some owned by families who could no longer maintain them after World War II, as well as miles of coastline and countryside that it opened to the public.

The group’s 5.37 million members pay £91 a year — around $115 — for unlimited entry into more than 500 sites. Even if you’ve never been to a National Trust property, you’ve probably seen one in a period drama. Parts of “Downton Abbey” were shot at Lacock in Wiltshire, while Basildon Park, near Reading, features in 2005’s “Pride & Prejudice” and seasons two and three of “Bridgerton.”

While the trust works to conserve history, it has always adapted, said Hilary McGrady, its director general, in an interview. “The very idea that we are potentially changing, I can see why that might feel unnerving,” she said. “The reality is, the trust has always changed.”

She noted that the houses didn’t always tell the stories of servants who worked “below stairs,” and that when they began highlighting those in the 1950s, there was pushback. “Yet we now think that’s entirely normal,” she said.

What Ms. McGrady can’t understand, she said, are the claims that the trust is on “a mad campaign to undermine history.”

Restore Trust was founded in 2021, a year after the National Trust released a report detailing the historical links that 93 of its properties had to colonialism and slavery. On its website, Restore declares that the National Trust is “driven by modish, divisive ideologies,” and calls for it to “restore a sense of welcome for all visitors without demonizing anyone’s history or heritage.”

Cornelia van der Poll, the current director of Restore — and a former lecturer in ancient Greek at a private Catholic college at the University of Oxford — has argued that the view of history presented at some trust properties “strayed” from its focus. In an emailed statement for this article she also pointed to what she said was “the loss of expert curators and the loss of authority of qualified experts in deciding how properties are managed and presented.”

The trust has said that its number of curators has doubled in the last five years.

Mary Beard, the classics expert and former Cambridge professor, told The Times of London that the 2020 report “was just stating the bleeding obvious: of course some houses have uncomfortable pasts.” She praised Dyrham’s treatment of its history as an example of good curation: keeping objects like the statues of the enslaved figures but contextualizing them.

On its website, Restore says it is “politically independent” and was founded by individuals. But the Good Law Project, a British governance watchdog, brought legal action to find out who was behind Restore and established that its website was owned by a private company, RT2021, incorporated in April 2021 with the stated objective of “Monitoring the activities of the National Trust.”

Ian Browne, the legal manager for the Good Law Project, said Restore masqueraded “as a grass-roots organization speaking on behalf of common sense” but had links to other right-wing advocacy groups. From 2021 until January, one of the group’s directors was Neil Record, the former chairman of the Institute of Economic Affairs, a libertarian think tank, and current chairman of Net Zero Watch, a group that denies that the world is in a “climate emergency.”

Mr. Record did not respond to requests for comment.

Restore also has the endorsement of right-wing figures including Nigel Farage, the Brexit campaigner now running for Parliament.

Dr. van der Poll said: “We receive donations and help from thousands of supporters. We believe that is a fair definition of a grass-roots campaign,” and declined to elaborate on Restore’s funding.

Before the National Trust’s meeting last November, Restore flooded social media with ads and pressed its position in numerous articles and media appearances.

But on the day of the meeting, a record number of National Trust members — 156,000 — cast ballots and rejected all the initiatives and candidates backed by Restore.

Its agenda had stoked some pockets of tension, however. After the result was announced, one man shouted, “You rigged the vote!”

The broader result may reflect the British public’s disdain for culture wars, experts said, with many telling pollsters that they crave a quieter, more civil political discourse.

According to 2023 polling by University College London and More in Common, only 27 percent of people said “tackling political correctness and woke issues” was one of the most important issues facing the country.

The same study found the National Trust to be one of the nation’s most respected institutions. By explaining rather than removing contentious historic objects, the trust showed that it “respects people enough to be able to make up their own mind,” the study’s authors wrote.

Some trust members said the “anti-woke” campaign had driven them to show stronger support for the group.

Judith Martin, 70, a member for decades, said she began attending the annual meetings only to make it clear Restore did not speak for the majority.

“There are already such limited resources, to try to split us like this, and cause these rows, I think it’s horrible,” she said, adding, “This fabricating of a culture war, I think it is despicable.”

‘A Gentle Acknowledgment’

On a visit to Dyrham late last year, visitors enjoyed tea and scones in the cafe after touring the house. Young families rambled Dyrham Park’s rolling hills. Older couples walked hand-in-hand around restored gardens.

A new sign near the figures of the enslaved men says they “cast light on the realities of the late 17th-century colonial system,” before informing visitors of an alternative route if they “wish not to encounter the objects.”

A specially commissioned poem laid on a table nearby reflects on “a world in which so much pain could exist alongside so much opulence.”

Sally Davis, 60, said the displays offered a “gentle acknowledgment” of the past.

Ms. Davis, who is white, and her husband Richard Davis, 63, who is Black, visited with their 2-year-old granddaughter, who toddled down a pathway outside the house.

They live nearby and come here often, they said. Mr. Davis, whose parents are from Jamaica, was glad for the deeper context, particularly in the case of the kneeling statues.

“When I first came here, the guide was a little bit apprehensive when those figures were there, and I said, ‘Look, you don’t need to be worried about it, it’s just one of those things,’” Mr. Davis said. “But you’ve got to have it out there so that people can understand how places like this came about.”