New research has revealed the extent of the British monarchy's involvement in the transatlantic slave trade, documenting the participation of kings and queens in Britain’s trafficking of enslaved African people over several centuries. A historical record known as the Register of British Slave Traders identifies thousands of investors, including members of the royal family and elite society, who profited from Britain’s role in enslavement.
Historians conducting the research uncovered evidence that enslaved Africans were forcibly branded with hot metal marks bearing the royal crown. Documents from the archives of the South Sea Company, a crown-backed enterprise active in the 1700s, indicate that company directors explicitly instructed their agents in Buenos Aires to use branding as a method to mark enslaved people. Despite warnings from a company-appointed doctor about the risks of this practice, the board insisted it was “the most effectual” way to distinguish enslaved people owned by the company from those held by others. The branding was to be applied to the left shoulder with a heated crown-shaped iron.
Dr Nicholas Radburn, a historian at Lancaster University and a lead investigator on the project, described the letter ordering the branding as a stark illustration of the calculated cruelty underpinning the slave trade. He noted the detailed consideration given by members of the London elite in planning acts of violence against enslaved Africans overseas.
The research highlights how the British monarchy institutionalized its involvement in the slave trade, particularly after the monarchy’s restoration in 1660. James, Duke of York—later King James II—served as a governor and prominent investor in the Royal African Company (RAC), established in 1672 and responsible for trafficking more enslaved people than any other single organisation in history. The RAC and its predecessor, the Company of Royal Adventurers, were founded with backing from King Charles II and senior courtiers. Meetings where decisions regarding the trade were made were held in James’s private apartment in Whitehall Palace, underscoring the direct royal oversight.
Professor William Pettigrew, the project’s lead historian, emphasized the central role of the Stuart monarchy in supporting these companies and, by extension, the slavery enterprise. He identified King James II as a key figure in driving the crown’s involvement.
The Register of British Slave Traders builds upon decades of European slavery research and incorporates data from the Slave Voyages database, a collaborative academic project initiated in 2008 documenting the ships, numbers, and mortality rates involved in the Atlantic crossing. The register extends this work by detailing investors who funded Britain’s slave trading ventures from the mid-16th century until the abolition of the slave trade in 1807.
Among the royally chartered companies profiled in the register are the Company of Royal Adventurers into Africa (1660), the Company of Royal Adventurers Trading to Africa (1663), and the Royal African Company (1672), which together trafficked approximately 195,000 enslaved Africans. The South Sea Company, created in 1711 and supported by the state, is documented as having trafficked around 45,000 individuals.
The project also traces how the monopoly of the Royal African Company was challenged and ultimately broken from 1689 as private traders lobbied for access to the trade, contributing to its expansion through ports such as Bristol and Liverpool.
In total, the research identifies roughly 13,000 investors in Britain’s slave trade over nearly 250 years, aiming to provide “the most comprehensive examination of a nation’s slave traders ever attempted,” according to Pettigrew.
The Register of British Slave Traders is a collaborative effort by Lancaster University, the University of Manchester, and University College London, funded by the Arts and Humanities Research Council. The work was directed by Pettigrew, alongside co-investigators Dr Nicholas Radburn, Professor Edmond Smith, and Dr Nicholas Draper, with a wider research team and advisory board comprised of specialists in the field.