This year has seen a dramatic change in tone in the global conversation about the transatlantic slave trade. The demand for formal apologies, debt relief and financial compensation from nations and institutions that benefited from slavery has become increasingly forceful. In March, a resolution was passed at the United Nations recognising slavery as "the greatest crime against humanity" - though the United States voted against the resolution and every European nation abstained from the vote. The UK, which alongside Portugal dominated the transatlantic slave trade, has consistently rejected the idea of paying reparations, which is perhaps unsurprising given estimates of...