The point about Bellamy is simple Jim, he not only performed traditional songs, but also songs he had written himself, performed in exactly the same style, and to the uneducated ear it would have been difficult to tell the difference. So if that new song is not a 'folk' song, what is it?

At what point does that new song cease to be what ever it is and become a folk song. It's still the same song.

I've had the pleasure of hearing songs I've written sung by other people, and the even bigger pleasure of packed marquees at folk festivals singing along when I've performed those songs, does that make them 'folk' and if not, what are they?

If I'm following what I think you're saying correctly then whatever is the current number one could become a folk song if people are still singing it in, say, 100 years time, or a piece of classical music written 300 years ago and still being performed regularly is now folk.

Surely 'folk' is about a style that maintains a tradition and not about age?