The union of the neighbouring episcopal sees of Lismore and Waterford on 16 June 1363 brought to an end a history of disputes and sometimes violent disagreements between the two bishoprics which had lasted for almost two centuries since the arrival of the English invaders in Ireland. The early history of this conflict, up to 1228, has already been dealt with in detail, while its conclusion, from 1325 onwards, has also been treated in outline. What happened between 1228 and 1325, however, has never been discussed, and while this note does not in any way purport to fill this gap, the document upon which it focuses, which dates from 1285, adds something to the stock of knowledge on this topic. It has been in print in summarised translation for well over a century, but it has never been published in full, analysed or put in context, and it has been quite ignored in all previous discussions of this controversy. It gives rise to some interesting questions about the relationship between the English and Irish administrations at the end of the thirteenth century, however, and about how important decisions were taken at the heart of Edward I’s government. It also casts intriguing light on a difficult time in the career of Stephen of Fulbourn, bishop of Waterford, perhaps Edward Fs most important and powerful servant in Ireland until his death in July 1288.