And RB if you're including Tangerine Dream in 'rock' then Comus counts? Song to Comus If I remember rightly, my parents saw Comus along with King Crimson at the Wheeley rock festival.. (see here )
All before I was born of course, though I think my 'spirit' has been badly touched with a good 2nd hand dose of hash and LSD. The first song I recall hearing: 21st Century Schizoid Man.