The group:
called themselves on the spur of the moment (just a group of friends that came to the festival):
MARSHALL BRICKMAN AND TROUP
Marshall Brickman (later a comedy writer for the original Sat. Night Live in the Belushi-Murray-Radner-Chase years)
Danny Kalb who played behind many in the '60s and was a member of Dave Van Ronk's jug band
Eric Weisberg (later one of the Tarriers and the 5-string wizard who played "Dueling Banjos" in the film DELIVERANCE)
Paul Prestopino (who backed up the Chad Mitchell Trio after Jim McGuinn (later called Roger in The Byrds) left that job. He was "Jim" in Chicago when he was in highschool and a part of THE FRETS, a trio with John Carbo and Louis McDonald -- the house band for the Sunday afternoon hootenannys at the original folk mecca/club, the GATE OF HORN, in Chicago.1959
and two others I can't recall.

The female singer was the young and freshly arrived in the USA, JEAN REDPATH. She sang "THE SONG OF THE SEALS" and mesmerized the entire audience. Since then I found it sung by the grand tenor, JOHN McCORMACK (around 1908).

Art