With its slavery list, the National Trust makes a welcome entry to the 21st century

It seems a fair bet that anything held up as an abomination by, among others, Oliver Dowden, Ann Widdecombe, Jacob Rees-Mogg, Simon Heffer and Andrew Roberts must have something going for it and the National Trust’s new report on links to slavery and colonialism at its properties does not disappoint. Far from it. I might even sign up.

Even for anyone who never visits the trust’s historic houses, this interim document offers some admirably clear, informative summaries of Britain’s participation in the slave trade and its colossal takings from the empire, the people this killed, the people this enriched, the houses, land and factories they accumulated with the proceeds and the political platform these assets then provided for the further advancement of slave owners’ interests. The compensation extracted as the price of abolition introduces more trust connections including, notoriously, Penrhyn Castle. Its builder, one Dawkins-Pennant, an opponent of emancipation, received £14,683 17s 2d for being deprived of 764 enslaved people.

Abolitionists and their connections in NT properties also feature in a report that has so enraged Widdecombe that she told Jeremy Vine, in what must rank among the most prized gifts in National Trust history, that she would be renouncing her membership. Although it’s not clear she has actually read the full report or, indeed, a word of it, she was particularly exercised by the inclusion of Wordsworth’s and Churchill’s homes in the list of reappraised locations. Churchill, she said, was not “personally connected” with slavery. Correct. The trust mentions Churchill’s premiership during the Bengal famine and his opposition to Indian independence. It was Churchill, again, who inspired in Dowden, the culture secretary, a rare flash of something almost resembling cultural engagement. Dowden said criticism of Churchill would “surprise and disappoint people” and that the trust should be “protecting our heritage”. Maybe there is hope for British theatre and music, after all?

Aside from complaints about deficient reverence for national heroes, it is difficult, however, to separate the objections to this particular report, from regularly – often justifiably – voiced suspicions that the trust is dumbing down, planning to sideline or bury anywhere it can’t pollute with signage, picnic tables and idiot exhortations. Regrettably, to judge by the repetition of the word “woke” in discussions of its new research, the complaints all seem to have merged.

Only the month before Widdecombe had to spring to Wordsworth’s defence (her abhorrence of “just for a handful of silver he left us” must wait for another Jeremy Vine), a leaked document revealed, in excruciating jargon, management doubts about historic interiors and the employment of specialists, with a condescending proposal to “flex its mansion-offer to create more active, fun and useful experiences that our audiences will be looking for in the future”. When, following Covid-19-related losses, the trust announced 1,200 redundancies, this, too, was interpreted as a further deliberate retreat from responsible curation.

For some critics, a focus on the barbarity behind some NT treasures represents yet another betrayal of the duties of connoisseurship, even if what underlies their discontent seems to be a curiously unscholarly wish for historic properties to be assessed strictly according to values prevailing when the trust’s James Lees-Milne was picking them up by the dozen in the 1940s. Ham House in 1942: “Superlative interior treatment, the panelling, the exquisite parquetry floors, the extraordinary chimney pieces…”

Also Ham House, but in 2020: one occupant was “Commissioner of the Council of Plantations (from 1671) and, when founded in 1675, one of the Lords of Trade and Plantations”.

Maybe it really was better to think of, say, the incredible gardens at Studley Royal as (in a more indulgent NT introduction) “the result of a breath-taking vision from John Aislabie”, as opposed to (in the new report) the consequence of Aislabie’s disgrace after he took a £20,000 bribe to promote the South Sea Company, founded to deliver enslaved Africans to the Spanish colonies. “Many individuals associated with National Trust houses invested” in the company, we learn, other relevant properties including Clevedon Court, Stourhead, Wentworth Castle and Polesden Lacey.

Undoubtedly, visiting was prettier when the public was encouraged with the help of guidebook hagiography to view such houses as their former owners would have wished, as the hallowed product of dynastic talent, intellect, even – farcically, in many cases – discernment. From the time the organisation went into stately home protection (not anticipated when the trust’s founders envisaged acquiring land for the healthy enjoyment of the non-landed), it became committed to portraying the country house, as this report says, as the towering expression of English history and therefore worthy of the public’s protection.

“This ‘English history’,” writes Dr Sally-Anne Huxtable, the trust’s head curator, “was a history of grand architecture, interiors, collections, landscapes and gardens that located the country house as a site of precious heritage.” Under management by actual grandees or hangers-on, this ideal persisted for years unmodified by considerations of domestic misery and exploitation or the possibility of non-philistine alternatives to the fanatical conservation that has twice moved the trust to restore houses it accidentally burned to the ground. Now, even the perspective of mid-20th century conservationists appears to some traditionalists to deserve perpetual conservation.

Supposing the trust does seem touched, in some of its new property entries, with decontaminating zeal, you could see this as a long-overdue and welcome rebalancing, from which still more thoughtful approaches to contextualising will emerge. No less than Lees-Milne’s focus on exquisite parquet, the trust’s slavery and colonial report is of its time – that of Black Lives Matter – and the better for it. Although it might perhaps have benefited from some more detail, such as Lees-Milne’s note, written after a late lunch in 1942: “Mr Churchill is a disastrous man. I hate him more and more.” God knows what Oliver Dowden would have thought.

• Catherine Bennett is an Observer columnist