“So little is known of the separate traders,” lamented the historian of the Royal African Company, K. G. Davies, that he was reduced to perceptive speculation about their activity. The authority, Basil Williams, writing about the period 1714–1760, asserted, “The traffic in negro slaves was carried on mainly by the Royal African Company.…“ In actuality a great deal can be discovered about the separate traders and their activity. The papers of Humphry Morice provide a rich source for a merchant who was perhaps London's and Great Britain's foremost slave trader in the 1720s. The assertion that the traffic in Negro slaves was carried on mainly by the Royal African Company is easily refuted by materials in the Public Record Office. London separate traders dominated the trade for the first three decades of the eighteenth century giving way to Bristol traders in the 1730s, who in turn gave way to Liverpool ascendancy in the 1740s.
The English slave trade between 1699 and 1729, energized by the end of monopoly and the booming international market for slaves in America, grew prodigiously. In these years England accounted for nearly one-half of all slaves exported from the west coast of Africa. London alone accounted for two-thirds of all slaves delivered by English ships.
Although the period falls half a century and more before the classic exposition of the advantages of free trade over monopoly by Adam Smith, an English free trade doctrine had found expression in Sir Dudley North's pamphlet, Discourses upon Trade (1691), and parlimentary proceedings. Interlopers in the slave trade, smugglers in the lucrative Spanish-American trade who opposed parliamentary restriction on their activity, separate traders whose participation in the trade became legalized in 1698, and a variety of commercial, industrial, and planting interests all contributed in their fashion to an outlook favoring free trade in slaves.