"So, are you claiming that all of the collectors you mentioned abide by your "definition""
I am saying there is a consensus among academics and researchers
That doesn't mean that all collectors collect just folk songs - we tried to collect C and W songs from Mary Delaney but she dismissed them as unimportant
Walter Pardon did the same with his large repertoire of music hall songs and Parlour ballads - we have a long interview with him describing how he regarded them as different from his traditional repertoire   
If you want the tradition English repertoire, google the Roud index and work your way through it
"That does not mean that it cannot exist happily alongside other forms of music."
Of course it can Nick, but not in a folk club - why not run music clubs or song clubs - I've enjoyed plenty of those
When you suggest that one is the other, you blur the lines but What is being argued here is that those lines don't exist.
The old singers thought they did - hence Jean Richie's story
Jim Carroll