"It's always going to be very difficult to provide a smoking gun for a lot of these songs, since most broadsides were anonymous, and in any case there's always the possibility that another version existed before the oldest known copy."

Of course - that's why I'm interested in the assertion that most of them were probably written by professional urban writers or poets. If most of them are anonymous, and we don't have bookkeeping records of broadside printers and their scribes, where does this "probably..." evidence come from? Is is just simple assumption: that the earliest broadside printing of a given song "probably" means that was when it was written? That's an eminently reasonable presumption, but it's still a presumption.

I'm interested in these "probablies" and that 90–95%, not because I'm unwilling to be disabused of any romantic notions, but because I'm genuinely curious as to why there are so many odd folk songs in the canon. If, as Roud's own research suggests, broadsheets about scurillous murders were the biggest sellers, how have we ended up with so many pastoral folk songs with often quite arcane words and practices?

Sure, I can see why all those songs about lads and lasses rolling in the meadows could have come about, but what would have been the motivation/inspiration for an urban professional writer in writing a song that facilitated seasonally-based begging at the Big House with opaque lyrics about wrens and/or sprigs of May? (And not just one, of course, but whole schools of them?)