Not to dispute Chris Ball's authorship, but never assume that a copyrighting a song guarantees it's traditional. In facts, there are lots of copyrights of traditional anonymous songs by recording artists. Even Paul Simon and Bob Dylan did it. The reason they do it is to claim the composer and lyricist royalties. The copyright office automatically approves any application that is the first one for a song, and leaves challenges to fight it out in court. Of course, if you obtain a copyright for a known traditional song and attempt to enforce it against other recording artists in court, the court will shoot you down.