From A Compendium of Irish Biography, 1878
Flannan, Saint, a confessor and Bishop of Killaloe, 639, was the son of Turlough, King of Thomond. Educated in the monastery founded by St. Molua, he ultimately retired to Lismore, where he was joined by his father, who resigned his throne. We are told that he spent much time in this retreat between "the soaring mountains on the north and the thick and extensive forests on the south." Archaeologists have maintained that the traces of artistic taste acquired during a sojourn in Rome are evident in the churches erected by St. Flannan in Munster. He died "full of years," and was buried at Killaloe, of which he was the first Bishop. His festival is the 19th December.
119. Ecclesiastical History of Ireland: Rev. John Lanigan. 4 vols. Dublin, 1822.
134. Four Masters, Annals of Ireland by the: Translated and Edited by John O'Donovan. 7 vols. Dublin, 1856.
235. Martyrology of Tallaght, with Notices of of the Patron Saints of Ireland: Rev. Matthew Kelly, D.D. Dublin, 1857.