Notes from the back of the Cynthia Gooding album (the Tasmanians came through!):

Known also as Lady Alice (child 85) and Giles Collins (Sharp), taught to her by a friendly amateur folk singer. In earlier versions, the lady is sewing at her window when "the handsomest corpse she ever saw" goes by. As time passed, the emphasis changed and the structure of the song has been greatly simplified.

Fascinating. Still no mention of a Silkie...