From Thomas Walsh's History of the Irish Hierarchy chapter lix, p. 632 ff:
Loughkey. The river Boyle runs through this lake in which there is an island called Trinity Island, an abbey dedicated to the holy and undivided Trinity having existed there AD 700.
AD 1215 the eminent Clarus Mac Moyhn O'Mulchonry, archdeacon of Elphin, refounded this abbey under the invocation of the Holy Trinity for Premonstré canons. He also founded the church of Deryndonne.
AD 1231 on the 15th of December died here Dionysius O'Morra, who had retired from the bishopric of Elphin.
AD 1234 Gillisa O Gibbellan anchorite of this island died.
AD 1239 Lasra Fina, daughter of Cathal Croivdeargh and wife of O'Domnail, granted to this abbey the half townland of Rosburn, being part of her dower.
AD 1380 the abbot who was son of MacDermod Roe died.
AD 1440 the abbot died.
AD 1466 the abbey was consumed by an accidental fire caused by the negligence of a woman. This abbey was filial to the abbey of Premonstré in France. Its possessions were granted with other property valued at 26 13s 8d annually to Robert Harrison for ever in free soccage. The annals of Loughkey were preserved here.