Children's literature authors are notoriously hostile to Hollywood and it's attempts to adapt their stories. Roald Dahl (though he reportedly often appeared on the set before the movie's premier, according to people like Julie Dawn Cole ) hated this movie; and was very vocal about his distaste with the press. A year before this Norton Juster, the author of the similarly themed Phantom Tollbooth, was also very critical and hostile towards the Chuck Jones/MGM joint film production of his story which came out in 1970 and starred Butch Patrick. And 2 years after Chocolate Factory's premiere EB White trashed the 1973 Hannah Barbera version of his classic Charlotte's Web, calling it a "travesty.". And CS Lewis was so worried about a bad live action movie version of his Chronicles of Narnia coming out that he wrote a letter to the BBC forbidding them to do a film version of his stories. PL Travers also hated Mary Poppins in addition to all this. The irony is all these movies did come out; most of them were box office hits; all of them were warmly greeted by the critical community; and all of them are regarded as classic children's films by the public. In fact these movies have ironically only solidified these books' classic status in the cannon of children's literature.