Ok. Got that, Jim. The performance is as important as the song. I can go with that. So, in addition to your other points, the song has to be sung in a folky way to be considered in the folk idiom. Yes?

I am not sure what point you are making about the singer though. I agree fully that Rod Stewart's recording of Wild Mountain Time does not pass the test but what if he were to sing it unaccompanied in a folk club? Not likely I know but I am trying to establish if who is singing has a bearing rather than how they are singing it.

The other question I asked is does the melody come into it and, if so, how do we measure that?