P L Travers

It took more than 20 years to convince the author of Mary Poppins to sell the movie rights.

It all started in the early 1940s, when Walt Disney told his daughter Diane that he would make her favorite book into a movie. He was probably assuming that any author would be thrilled to hitch her name up to the Disney wagon, but quickly discovered that P.L. Travers was not just any author. For more than 20 years, Travers refused to deal with Disney. It was only in 1961 that she finally relented, mostly because she needed the money.
 http://mentalfloss.com/article/58615/18-supercalifragilisticexpialidocious-facts-about-mary-poppins