I'm looking for a film which featured Tom Baker as an evil magician (and no, it's not "The Golden Voyage Of Sinbad", that would be far too obvious). The plot concerned a young man whose mother is a witch, and who has to survive the seven curses of... somebody or other (Tom Baker's character). The boy's mother changing herself into a puma (or a lion?) was a significant part of the action. The young man's sword was supposed to open things like hidden doors. I also recall a stop-motion ogre, and a lot of very tiny people (leprechauns, possibly?) using the hero's sword to saw through the ropes binding him. The hero may possibly have been called "George". There's a scene in which the mother announces she's going to double George's magic, but it all goes wrong and his sword, etc. become entirely non-magical for a while. Any suggestions (other than "lay off the hallucinogens, Nicolas")?