Sir's Don McLean LP sleeve with liner notes by Pete Seeger does not surprise me. I seem to remember (circa 1972?) listening to my portable radio while stopping in a bush hut a friend and I built in the Blue Mountains, NSW, Australia.
I heard a track of Don Mclean singing a quite non-reggae "By The Waters of Babylon", with audience participation led by spoken cues. The general effect sounded remarkably like a very young Pete Seeger.