Little is known of the early history of the foundation. The modern name, White Island, only dates back as far as 1753. It is possible that White Island may be the ancient Eo-inis, from whence the relics of St Constas were translated to the cathedral of Clogher by Bishop Matthew Casey (1287–1315) (Rogers 1967, 67). Archaeological excavation has revealed some evidence of a wooden church on the site of the existing stone church, and there is evidence that the interior has suffered severe fire-damage. The doorway was apparently restored at some time during the late medieval period and photographs from the 1860s show the jambs of the door with a distinct outward inclination. By 1913 the arch and E jambs had collapsed and in 1928 the church was restored by the Belfast Natural Historical and Philosophical Society. The site is currently in care of the (Department of the Environment, Northern Ireland) DOENI.