The joke is that the British have an incredibly problematic history literally centuries-old of taking things from other cultures and going “well, it’s ours the world’s now.“ Many of these communities have been asking them literally for decades to return them, but they simply won’t even to this day.
There was a time where they could maybe make the claim “this is the best way to preserve them,“ but for the vast majority of cases that time has long since passed and it was flimsy to begin with.