It was built firstly for the convenience of any pilgrim wishing to go to St. Mogue's birthplace and secondly as an interment chapel for the few family members attending burials on the island.
Mandate to collate and assign to Magonius Macamragan, priest, of the diocese of Kilmore, if found fit, the perpetual vicarage, value not exceeding 6 marks, of Insula Brechungy alias Tempullapuret in the said diocese, collation and provision of which, on its voidance by the death of Andrew Macgamragan, was made to him by bishop Nicholas.
[1] The earliest mention of the name in the annals of Ireland is in the Annals of the Four Masters for 1496 A.D.- "M1496.17- Magauran, i.e. Donnell Bearnagh, Chief of Teallach-Eachdhach, was treacherously slain before the altar of the church of Teampall-an-phuirt, by Teige, the son of Hugh, son of Owen Magauran; and the marks of the blows aimed at him are still visible in the corners of the altar."
The parish was famous in ancient Ireland as the location of Magh Slécht and the centre of worship of the pagan god Crom Cruach.
The "Survey of County Cavan" held by Sir John Davis on 6 September 1608 (Analecta Hibernica Vol.3, 1931) states- Barony of Lissenouer alias Tullaghehaagh.