Jerry Garcia
Bill Kreutzmann
Bob Weir
Phil Lesh
Ron McKernan
Mickey Hart
Tom Constanten
Also Appearing
Crosby, Stills & Nash, Jefferson Airplane, and Joni Mitchell
Notes
ref: "Hyde Park flop as fans stay away," London Evening Standard, September 20, 1969, p. 10. Rock says GD had "turned down $120,000 in gigs to try and come to London," but circumstances did not permit it.
Apparently this was attempted for September 7th, as well. Strike two.