The Brothers Four, incidentally, were among the half-dozen or so folk-revival acts in the amusingly horrendous early-60s exploitation film "Hootenanny Hoot."

The film is mentioned in an old thread, currently refreshed, about Sheb Wooley and Shep Wooley. Sheb ~ the American actor and singer ~ appeared in the film and also, I believe, wrote the theme song.

Here's a link to the IMDB page on this movie:

"Hootenanny Hoot"

IMDB provides not only the cast, but also a complete roster of the musical acts. My favorite performance in the film, by the way, is a short set by the largely-forgotten Joe and Eddie.