The famous '14-Hour Technicolour Dream" show. And The Syn, who did not play, wrote a song about it!

Complete list of bands:
Alexis Korner
Barry Fantoni
Champion Jack Dupree
Charlie Browns Clowns
Christopher Logue
Denny Laine
Dick Gregory
Gary Farr
Giant Sun Trolley
Ginger Johnson and his African conga drummers
Glo Macari and the Big Three
Graham Bond
Graham Stevens
Jacobs Ladder Construction Company
Jean Jaques Lavel
Jimmy Powell & The Five Dimensions
John's Children
Lincoln Folk Group
Mike Horovitz
Noel Murphy
Pete Townshend
Pink Floyd
Poison Bellows
Robert C. Randall
Ron Geesin
Sam Gopal's Dream
Savoy Brown
Simon Vinkenoog
Social Deviants
Soft Machine
Suzy Creamcheese
The Block
The Cat
The Crazy World of Arthur Brown
The Creation
The Flies
The Interference
The Move
The Pretty Things
The Purple Gang
The Stalkers
Tomorrow
Utterly Incredible Too Long Ago To Remember Sometimes Shouting At People
Yoko Ono