On the other side of things, in the chapter on "The singing habits of sailors and soldiers", Roud quotes Herman Melville's (fictionalised, but presumably first-hand) account of Liverpool:

"But one of the most curious features of the scene was the numnber of sailor ballad-singers, who after singing their verses, hand you a printed copy, and beg you to buy... ... he composed many of his own verses, and had them printed on his own account" (Melville)

My Kindle says I am 65% of the way though the book, but there is not much of what seems contentious in this discussion that has not been touched on.