"Lord Thomas" is a very old and widespread ballad. It is #73 in Child's collection. It is probably second only to "Barbara Allen" in distribution. This is probably the bloodiest of the old murder ballads. I do an approximation of Mike Seeger's autoharp version - lots of fast chords but worth the effort. This was printed in the Burl Ives Song Book, Cecil Sharp's One Hundred English Folksongs and the New Lost City Rambler's Song Book.