13,000 investors financed Britain's trafficking of 3.3m enslaved Africans

William A. Pettigrew's Britain's Slave Traders reports nine historians tracing about 13,000 investors who financed British voyages trafficking 3.3 million enslaved Africans, with about half a million dying in the Atlantic crossing, according to The Guardian review of 23 September 2026. The book accompanies BBC Two's Finding Britain's Slave Traders.