Interestingly it was Dave Harkers earlier book "Fakesong" which gave an explanation of why English traditional song is so undervalued. I hope I am not misrepresenting his arguments which are from one reading a long time ago but as I understood them his thesis was that there is really no such thing as traditional folk, there is workers and peasants music. Potential ruling classes would take elements of this music, invent and codify others and label it 'Irish music' or 'Scottish music'. When you look at England of course the last thing our ruling class wants us to do is reunite our working class with their history of songs about Plug riots, WCaptain Swing, Peterloo, riots mutinies and crime.