I remember her from a Getaway back in the seventies. She has this presence, statuesque, white hair piled high(then, anyway) and the wonderful voice you hear and she takes no guff from anyone, so they all bring her samples to test out the theory. I recall the guys who sang behind her (Jonathan and..?)baahing when she sang "Feed my Sheep" and singing "fried liver" for "wide river" in One more River to Cross.
I also recall Gordon Bok, Anne Mayo Muir and Ed Trickett singing in concert a song -- Yarrow -- that they learned from her and introducing it by saying, "We're going to do this song that we learned from Helen, and we'd do it like her, but there are only three of us."
That kind of gives you the flavor.
Blessings,
Barbara