There can be few institutions which have so successfully eluded the serious historian as the Duchy of Cornwall, for only one aspect of its history and administration, that of its jurisdiction of the tin mines, has been adequately treated; its curious legal relation to the Crown, and to common law, its political importance in reference to Council and Parliament, and its economic significance as one of the largest landowners in England, all await detailed investigation. For such an enquiry there is abundant material available, both in the series of “Duchy of Cornwall Records” and “Miscellaneous Books” in the Augmentation Office of the Exchequer, at the Public Record Office, and in the fine collection of Ministers' Accounts, Assession Rolls, Court Rolls and other documents, preserved at the Duchy of Cornwall Office; a collection to which I am much indebted to Sir Walter Peacock, for giving me access and to Mr, Rollo Clowes, its custodian, for invaluable assistance in working at it.