The events leading up to the founding of the Psychological Laboratory at University College London are examined in the light of correspondence from James Sully to Francis Galton. The correspondence reveals the dependence of Sully on Galton for detailed advice at every stage of the process, possible reasons for which are discussed. It also provides sufficient clues to enable identification of a hitherto anonymous donor. Although Galton may have inspired and advised on the initial setting up of the laboratory, his influence on its work did not become apparent until after his death.