Again, a little note from the sidelines (and yes, thank you, George, I do know that the money comes from the pub licence and not individual performers - my point was a distinction between a session or singaround and a concert, which I also know isn't a possible distinction to make in real life) - on the subject of the "threshold" for joining PRS: When I first joined back in the 70s, the ONLY criterion for joining was a version of this threshold. There had to be a certain amount of activity with your compositions before you could be a member of PRS, and there were varying categories of membership to reflect this. So I didn't have to pay the £100 fee but did have to prove that my songs were being performed commercially (ie broadcast, on significantly sized stages or recorded). My guess is that a number of PRS members were reluctant to lose this element of "quality control" rather than have it as a purely "pay to join" organisation.
I'm with you, Jim, on the subject of traditional music. The problem is that the folk world has never only included traditional music - even reputed source singers would include songs from the popular musics of their area or their time within their repertoire.

Anne