Just in case Newport Boy is still reading, I thought I'd continue our sideline mini-discussion:

"Agreed in essence, Brian, but I was making a simplified point. I think "many hundreds" would be an upper estimate, and many broadside printers did not sing the ballads they printed. Some of the more productive kept a tame musician to do that (and also to adapt tunes for new words). I left them out mainly because their living was made principally from printing and selling sheet music (or words) and the discussion was about performing musicians."

Phil, I accept your distinction between musicians who were paid purely for performing, and sellers of song sheets, but I wasn't talking about ballad printers; I meant that class of people who earned their living by buying ballads at wholesale price and selling them on the street corners. Most of them attracted buyers by singing the ballads they had on their broadside sheets: all of those first lines that begin "Come all you lads of high renown" or "You gentlemen both great and small" etc. were designed to pull in listeners, like a busker's patter. My suggestion of 'many hundreds' is based on a 1641 estimate of 277 ballad singers in London alone, quoted in Marsh's 'Music and Society in Early Modern England' - if I'd wanted to be bolder I could have guessed at thousands rather than hundreds, since the sellers were active in market towns across the country as well as the cities.

Given that the majority of folk songs were at some point printed, that print runs ran to hundreds of thousands, and that very few broadsides were supplied with music, the singing of the ballad sellers must have been a very important way of getting the tunes into public circulation. I mention it just for interest, not to prove a point.