Steve- re the PEOPLE deciding the essence of folksong is exactly what I was trying to say!
It's the obsession with song origins and looking for chapter and verse regarding a song many hundreds of years old which I cannot understand! It's OK for academics, but I can't see the point?

As you rightly say, the PEOPLE choose- Jack Campin's statement that there is movement between various music genres is also something I accept but certainty about origins in this context seems unrealistic & not worth pursuing.