Theere was apparently also a gig at Marquee in London on June 24, 1970:
http://www.themarqueeclub.net/1970
Little Free Rock, who played on the same date, did some sessions with Green on his planned solo album, as mentioned before. Maybe also Ginger Johnson’s African Drummers, who may be the "african drummers" Green refers to in Martin Celmins' book.