Steve G said "I doubt very much if any of the contributors to this thread would differ on what constitutes a traditional folk song". That's probably correct for a central core of material, but we may well differ considerably about some of the layers further out: see the examples cited by Brian Peters at 08:25 AM Mudcat time today. Steve R himself sets out on pages 24 and 25 many criteria for something being "folk" or not, with particular instances meeting more or fewer of them to varying degrees. And a bit later he suggests that no specimen will ever score 10 out of 10.