I also first heard this song on Jansch's "Crimson Moon". I liked it very much. I thought the Fillimore version by ISB was a bit of a curiosity, but I would prefer to hear a simpler, punchier version.
By the way, was Mike Heron the same guy, who sang in Heron? I am talking about a three piece harmony group, whom I saw in Reading in the mid seventies? They featured the brilliant Gerald "GT" Moore on guitar. It was quite an enjoyable evening.