Though never considered a "Fifth Beatle," Nicky Hopkins was one of Great Britain's best-known session players particularly through his work with the Rolling Stones and after playing electric piano on The Beatles' Revolution...
http://youtu.be/7tArjxr2rA0This lucky crowd in Charlotte, North Carolina on Mother's Day 1984 got to see Mr. Hopkins perform with The Spongetones. He was in town promoting the L. Ron Hubbard movie Battlefield Earth, whose soundtrack he appeared on. The show was entirely unrehearsed...
http://youtu.be/bnvcIeyJ3RA44:30
Nicky Hopkins' frail health led him to concentrate on working as a session musician instead of joining bands. Sadly, Nicky Hopkins passed away on 6 September 1994 at the age of 50 due to complications resulting from intestinal surgery presumably related to his lifelong battle with Crohn's Disease.