I just checked Wiki and it says Palmer left Authur Brown to become a founding member of Atomic Rooster and jumped from there to ELP. I never even heard of AR until the 80s but I saw TCWoAB with Carl in 1968. That guy was as nutty as Screaming Lord Sutch (who employed Jeff Beck before he was a Yardbird).
Awesome! I never met anyone who had even heard of atomic.rooster! I saw them live in Wheaton, md when l was a kid