Roald Dahl based the character of Grandmamma on his mom (not his grandma). Like Grandmamma, Dahl's mom loved to tell stories about bizarre creatures (source).
The Witches was adapted into a stage play that you can put on with your class (or in your basement, playing all the parts yourself).
In the movie version of <em>The Witches</em>, the narrator has a name: Luke. Do you think this is a good idea? If you'd had to give him a name, what would it have been?