The Sailor and the Devil is a 1967 theatrical cartoon from Richard Williams Studio, animated by Errol Le Cain.
This was Le Cain's "Apprentice work," and he apparently animated the short single-handedly. A clip from this short appears in the documentary The Creative Person, showing the musical rhythms of the piece.
Shortly after its completion, there was a fire at 13 Soho Square which destroyed much of the artwork from the film.
"THE SAILOR AND THE DEVIL is a stylistic masterpiece, and the limited animation is fresh and unusual." - Hans Bacher.
Hans Bacher has posted grabs of what may be his own copy at his blog. A copy from an HBO airing from the late eighties was recently discovered, but appears to be missing some footage.