"King John and the Abbot of Canterbury." Where's the DT version from?

Below the DT lyrics is noted "recorded by Chris Foster", who released in in 1979 on his Topic album All Things in Common. His liner notes gave this synopsis:

King John and the Abbot of Canterbury … a song about a clash between church and state, including a shepherd with a misplaced sense of loyalty, three good riddles and a dubious happy ending.