I love the original but I remember when I first listened to this cover thinking if anyone would do right by Joni it would be Sandy Denny (well, all of FC at that time). and I've jammed Sandy quite a lot but never doing a cover. I think..
Joni Mitchell was first known as a songwriter and a number of artists had success with her songs before she had recorded them. Judy Dyble recorded this with Fairport Convention two years before Clouds came out with Joni Mitchell's own version. The Fairports were still performing the song, though by then Sandy Denny had become their singer.