Geoffrey Mason reports:
The event was free speech fundraiser organized by International Times (or IT for short), which was a London underground newspaper in print only at the time. Now it exists on-line only.

They did coverage of it leading up to the show and after April 1967. I've attached a nice large version of the cover of their special 14th Hour Technicolour Dream special (issue #12) here. You would probably want to link to their archived version of the issue:
IT - International Times Archive
[Link]

I've also attached 2 clippings from the issue of previous (#11) issue of IT giving some details of the event.

I've attached a newspaper advert for the event.

I've attached two color flyers for the event, but I don't know who designed them. The first horizontal one certainly looks like Mike McInnerney's work, but I am not sure.

BBC documentary series "Man Alive" has a video covering it that aired about 3 weeks after the event: [Link]

There was a 90-minute documentary "A Technicolour Dream" about it released from Eagle Rock Entertainment in 2008: [Link]

Yesgigs

Monday, January 9, 2017 12:25 PM

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