I found the Melody Maker, and Top Pops reports of this festivel (amongst a few others). If press reports can be believed or at least partially true, Yes went down very well indeed.
At this show, Yes performed: "Something's Coming", "Then", "It's Love" and then were joined by Jon Hendricks for "Everydays" (not "Then").
"It's Love" here pre-dates the 1971.07.23 Bronx, New York show by a while. Peter had mentioned that "It's Love" was a song they did in "Mabel Greer's Toyshop" so it has been around.