King Charles III has voiced his approval for an independent probe into the British monarchy’s involvement with the trans-Atlantic slave trade—the first time that Buckingham Palace has publicly stated its support for such inquiries. The unprecedented statement came after The Guardian published a previously unreported document showing King William III’s acquisition of a number of shares in a slave-trading venture, Royal African Company. Camilla de Koning, a historian at Manchester University, uncovered the document and is leading a wide-ranging investigation as part of her Ph.D. thesis at Manchester University. “As His Majesty told the Commonwealth heads of government reception in Rwanda last year: ‘I cannot describe the depths of my personal sorrow at the suffering of so many, as I continue to deepen my own understanding of slavery’s enduring impact,’” a spokesperson for the palace said Thursday. “That process has continued with vigour and determination since His Majesty’s accession. Historic Royal Palaces is a partner in an independent research project, which began in October last year, that is exploring, among other issues, the links between the British monarchy and the transatlantic slave trade during the late 17th and 18th centuries.” The spokesperson added: “As part of that drive, the royal household is supporting this research through access to the royal collection and the royal archives.”