Ilann’s feast day is listed as 2 Feb in the Martyrology of Tallaght and he was accorded a genealogy which indicated close kinship with the Ui Dunglainge kings of Leinster.

Iolladon, priest of Desert Iolladoin (now "Castledillon"), who had St. Criotan (11 May), of Magh Credan and Acadfinnech (on the river Dodder), and of Crevagh Cruagh, County Dublin.

The Castledillon Friars Stone, possibly erected for a 15th-century abbot of St Wolstan’s (four miles to the east), remained on the site until removed to the Visitor centre in Kildare town.

The absence of a crosier has been noted to suggest he was not a bishop, as accorded in folklore, and may have been abbot in the friary of St Wolstan’s four miles to the north east, perhaps after it was dissolved in 1541.

The last remaining headstone in the local graveyard bears the inscription:[citation needed] During the First World War, the British Army set up a firing range on "The Butts", McKenna's land in Castledillon.