Errol Le Cain's short film Sailor and the Devil was made in 1966, while Le Cain was working at the Richard Williams studio. I first heard about the film thanks to its brief mention in Denis Gifford's book British Animated Films; I later found that it has something of a following, despite being hard to see. From what I understand no complete print is known to exist, although Garret Gilchrist has a copy with only a few seconds missing, which he has recently posted online:
Back in 2010 Michael Sporn wrote a blog post about Sailor and the Devil, drawing largely on a 1960s PBS documentary and showing a few black and white stills, while Hans Bacher provides some colour shots, including the ones I used above. More recently Amid Amidi wrote a piece on the film, which also discusses Le Cain's other animation work.
More information about Errol Le Cain, who passed away in 1989, can be found at the website Errol Le Cain Legacy. Le Cain does not appear to have worked in animation for long - although it is worth noting that he worked with Pearl & Dean and Moreno, as well as Richard Williams - and instead established himself as a children's book illustrator.