I've had a crush on Judy Dyble since I got Fairport Convention's first album in 1970, several years after it was released, and heard her sing this lovely Joni Mitchell song. Here is a recent video of her doing it with Songs from the Blue House, "the world's best ever East Angliacana group." Four years ago I posted a video of her, along with Vicki Clayton and a protean version of Fairport, one of Britain's leading folk-rock groups, doing an obscure Dylan song in French (go figure), which you can see here. I also included a video of Fairport from the time of that first album, doing the driving rocker "Time Will Show the Wiser" with Judy on harmony, in my iPod Log 4.
Above is a clip of Judy singing "(In the) Dreamtime," a song she wrote with John Gillies, from her 2009 album Talking With Strangers. She's joined here on vocals by another of the legendary ladies of British folk, Jacqui McShee of Pentangle.