The following article provides significant new evidence of John Locke’s interest in Thomas Hobbes’s Leviathan (1651). The evidence derives from the collection of manuscripts amassed by the historian Thomas Birch (1705–66), the author of The History of the Royal Society of London (1756–7). Within this collection are several documents in the hand of Pierre Des Maizeaux (1672/3–1745), the Huguenot journalist and biographer. In 1718–19, Des Maizeaux set about compiling A Collection of Several Pieces of Mr. John Locke, a posthumous compilation of lesser known works and manuscripts by Locke, edited with the guidance of Anthony Collins (1676–1729). In preparing the volume, Des Maizeaux interviewed one of Locke’s friends, whose recollections he recorded in an anonymized memoir, in French. The article reveals that the anonymous friend was James Tyrrell (1642–1719), the Whig propagandist, and one of Locke’s closest acquaintances. Tyrrell’s claim that Locke ‘almost always’ had Hobbes’s Leviathan on his table in Oxford, c.1658–1667, is one of several in the memoir which revises our understanding of Locke’s intellectual development and the history of one of his best known friendships. The article contextualizes and translates the memoir, and revisits the debate surrounding Peter Laslett’s relegation of Hobbes’s significance to Locke’s political thought.