I love Joan Baez' version of Mattie Groves, and I also love Fairport's version. I found it worked great to set the Joan Baez version words to the Fairport tune (which is actually the same tune as "Shady Grove"). You can hear the result of this mix on my MySpace page . Stevie Mulholland, who played fiddle, hadn't heard the Fairport version and so made up his own fiddle accompaniment which I think turned out great.