Nice one to think about Dave.
You might also add The Copper's book of songs which fixed the texts of their repertoire.
On the other hand, the Travellers, basically a pre-literate group, had an enormous influence on the song tradition here in Ireland by having printed and distributing their songs on ballad sheets and selling them round the fairs and markets (wonderful dichotomy).
There are exceptions to all rules.
Jim Carroll
As you have stated your enjoyment of this thread in such glowing terms, I think this means you owe us all a pint!