So many of our fancy country houses were financed to some extent or other by money from slavery, but it's not something that has been openly acknowledged much until recently because there were so few slaves (comparatively speaking) actually in the UK so it's less visible in the history - so that's part of the push back, a kind of "but there's nothing to see _here_ so why bring it up?". But it does seem ridiculous that it's become an entire organisation devoted to seizing control of one of our big historic trusts in order to censor what can be said on information boards.