This just in:

[Disney Historian Jim Korkis has been working on a project about the books that Walt Disney read and might have influenced him. In the process, he got to talk with Diane Disney Miller and with the release of “Mary Poppins” on DVD recently, here is a little insight into Walt’s familiarity with the book:

Walt would find books anywhere. According to publicity for the film, he picked up a copy of “Mary Poppins” on the bedside table of his daughter, Diane, and that got him to thinking about adapting that story. “The Mary Poppins book, now an artifact in our exhibit (at the Walt Disney Family Museum in San Francisco), was sent to him by the publisher, who inscribed it "Dear Mr. Disney .. This is not Mickey, but we think you'll like our Mary." It had been in our home years before I could read, and I'm certain that he'd read it before he picked it up from my bedside table,” Diane Disney Miller wrote to Jim.]