 There is reason to suspect that Dúnán was Roolwer's antecessor in the Isles.This would mean that when Dúnán died in 1074—only a few years after the takeover of Dublin by Toirdelbach—the latter oversaw the ecclesiastical separation of Dublin from the Isles through the creation of a new episcopal see in Dublin.Therefore, like Gilla Pátraic in Dublin, Roolwer's episcopacy in the Isles may well have begun in 1074 after Dúnán's death, and perhaps ended at some point during Gofraid Crobán's reign.