"I thought you were referring to embellishment, improvisation of melody of the tuneETC .Which is certainly different from Sharps bowdlerisation of the Keeper."

Again, I'm really not seeing the difference.   People complain about "embellishment" or "improvisation" of a tune, yet it is acceptable that that people like Sharp changed words and created piano accompaniment?   How is that different?   Neither one remains true to the source.

It is obvious that everyone has a slightly different definition of the words "folk" and "traditional". You can argue semantics, but the bottom line remains the song.   If 100 years from now "folksingers" are sharing "I Gave My Love a Cherry" and "All You Need is Love", then it will probably be a healthier world.