The centralising administration of King Edward I in Ireland, between 1272 and 1307, determined to disable the authority of all Gaelic kings, irrevocably. This process is reflected in Crown documentation which, soon after 1300, addresses major Irish leaders as duces (leaders) rather than reges (kings) and sometimes just by their names with the distinguishing qualification hibernicus (Irish).2 Freya Verstraten has pointed out that the replacement of the title rex with dux, seen as early as the mid-thirteenth century in government documentation, is mirrored in Vatican documents, where one finds Donnchad Cairprech Ua Briain, King of Thomond, referred to as dominus (lord) by Pope Innocent IV (1243-54).3 In those rare instances when the term ‘king’ was used by the Crown as a form of address to Gaelic aristocracy during the fourteenth century, it was, as Robin Frame observes, applied with contempt and used ‘only to describe lesser figures who presented no threat’.4