Pavane said:

On a similar theme, if a singer presents his OWN material but claims that it is a traditional song he collected (not an unknown occurrence), then presumably he cannot claim any copyright?

John Jacob Niles did that, I've been told. He represented "I Wonder as I Wander" as a collected folk song, but when someone else used the song Niles sued, claiming it as his own, which it was.

Dave Oesterreich