interesting 1974 Clive James on the successes and failures of Sandy Denny--

"Here, had she but known it, was a straight message from the Muse: the text of "Tam Lin" should have told her that the language of the past is too alive to be copied, and can only be competed with by the language of the present. As it happened, she went on to attempt a contemporary folk language composed mainly of archaisms, and so was unable either to extend the resources of the modern song or add to the heritage of the ancient one -which was composed, in its time, not out of scholarship but out of the language of the day. Swarbrick�s excellent edition of "Tam Lin" (there are dozens of versions, but his is of exactly the right length and dramatic structure) has the continuous linguistic interest by which a strophic song can gain from its repetitive form, and inversions like "as fast as go can she" fall with a naturalness that no modern writer can possibly match. She sang the song with dazzling attack, as alive to its theatrical force as she was deaf to its lesson..."