Sir Thomas Duffus Hardy (1804–78) was Deputy Keeper of the Public Record Office and an experienced medieval manuscript scholar, having edited the Monumenta historica Britannica after his mentor Henry Petrie's death. Hardy was closely involved with the Rolls Series of publications of medieval manuscripts in public ownership, a government-backed project, of which this catalogue (consisting of three volumes in four parts) forms part. His stated aim was to list 'all the known sources, printed or unprinted, of English history' in a handbook for historical researchers. Each item, from early mentions of Britain in Herodotus to medieval chronicles and saints' lives, is located and described, and, where Hardy has examined the original, the first and last lines are given. Where known, the author's life is briefly outlined. The first part of Volume 1 (published in 1862) includes sources from the classical period and the Dark Ages up to 750 CE.