Stashed in the National Archives in London’s leafy suburb of Kew are hundreds of boxes of documents marked T71. Each of the sepia-coloured sheets inside them holds handwritten details of estates and slaves, including how much each “negro” was worth, creating the most extensive known paper trail of slave owners in the UK’s former colonies.

For 170 years, the papers remained unexamined, allowing companies, families and institutions that knowingly profited from slavery to conceal their links to the trade and keeping those who were unaware of them in ignorance.