In prison Grafton compiled an "Abridgement of the Chronicles of England", which he published in 1563. It includes the first published English version of the verse "Thirty Days Hath September...", although manuscript versions have been found from the 15th century. To this he added in 1568–9 "A Chronicle at Large". Neither holds a high place as authorities, as they lack original material. John Stow and Grafton had a running battle over their rival chronicles after Stow justifiably accused Grafton of copying his own work. In the "Chronicle at Large", he is the earliest writer known to refer in print to Edward of Woodstock (Prince of Wales, Duke of Cornwall, Prince of Aquitaine) as the "Black Prince". The origins of the name remain uncertain: Grafton said he had found it in other writers, and gives no further explanation.