'To return to the original question, a new song can only become a 'folk song' if it goes through a process of acceptance and moulding by a community of people which turns it into something different from the original. However it can still be 'folk' if it meets the accepted stylistic conventions which that label implies.

Actually Howard, I think you may have cracked it there, that's probably the most sensible statement I've seen on this thread, although you will still have difficulty with some, who if you look back, maintain that 'folk' is not a style!

John