"PG was worthy of a blue plaque."
Totally in agreement with that, unfortunately he fell victim to a folkie hitman, as did others of his time
The views expressed then are unfortunately on the rise again, robbing us of the opportunity to make an overall assessment of the work of some of our early pioneers - who had the advantage of wotking with live performers from a living tradition.
I have a full set of the English Granger recordings, I believe they are among the most neglected examples of early English singing)   
A handy little work is Jane O'Brien's music monograph, 'Grainger's English Folk Song Collection' an annotated index of the songs he collected
I got outs in a second hand bookshop in Chiswick (for £1) but have never seen a reference to it since - well worth searching for
He also recorded in Denmark - I've often wondered what they sound like
Jim Carroll