This episode is one of the later color presentations with much better resolution than its black and white predecessors. The plot is based on the well worn themes of wrong vs right with no room for middle ground and therefore lacks shades of grey. In that it is a moral play about the injustice of omnipotent monarchs and their insatiable desires and greed it was great fare for young viewers.
The female lead, Patricia Kneale (best known for the thought proving science fiction series "A for Andromeda") made her television debut in this episode and provides a fetching and plucky foil to the evil King. All in all, an enjoyable escape!
Link to the book:
The Adventures of Sir Lancelot - 20 Maid Of Somerset