Disney fooled me and I thought that this was a theatrical production, so I watched it. This is actually a made for TV from the 1960s. But honestly, it doesn't differ much from their live-action of the time. There's a vague historical aspect, a lot of British actors, and a very out of place American accent. The story more or less sticks to the plot of The Mark Twain original, but it is done with more of a divine right of kings Flair. It is clear that the poor boy would make a better King, is making a better King, but he gives it all up when the real king returns from his adventures. It would have been a much better film if the boy had decided, i'm the king now take this Ruffian and throw them in the tower. The real King dies at the age of 15 which the film barely hits at, although they do suggest that his sister Mary was a fanatic. Although Elizabeth the first, barely mentioned and that's probably because this film was made during the early years of the reign of Elizabeth II.
