Literacy played little part in preserving our ballad repertoire in the tradition - there is a great deal of difference between being able to read and using the skill [...]
This was brought home with a storyteller we recorded who gave us a version of the epic tale 'The Pursuit of The Gilla Dacker'. We found a published version in P W Joyce's 'Old Celtic Romances' and asked the storyteller if he knew of it.
"Yes", he said, "but he's got it all wrong; those fellers never got it right".

If the written text was inaccessible to him, how would he have known it was wrong?

With notated music, anybody who wanted a tune out of a book was rarely very far from someone who could read it for them. Hand-copied manuscripts by local musicians are found from all over Britain since the 18th century - for every illiterate blind fiddler there was a sighted and literate one who could teach him anything popularized through print. Transmission from paper into orality wasn't a one-off event like Laplace's model of God setting the planets spinning, it was an ongoing process renewed in every generation. Why should it have been any different with song texts?