"Whoever may read these books about St. Columba's miraculous powers, pray to God for me Dorbbene that after death I may have life eternal."
Adomnan's work was written c. 690 AD. I don't know when Dorbbene made his transcription, but he was a successor of St. Adomnan, not more than nine years after the latter's death. That means that in early Celtic Christianity, often noted for its development free and clear from Roman influence, prayers for the dearly departed were firmly in place -- so much so that a transciber would seek out the prayers of his readers.
The Catholic apologist will note that prayers for the dead are recorded within the deuterocanon, and that may very well be true. So I don't raise this point to surprise anyone at the ancient pedigree of such prayers. I'm just [b]logging my interest in the note concluding the transcription, and the Protestant's inability to attribute this to "papish" influences.