"[Travers] wanted to get what she felt was the quirky nature of Mary Poppins into this," he said. "[Mary] is a firm rock in a very unsteady world."
But Mackintosh also knew that a successful stage production would need the musical pedigree that includes some of the most famous Disney songs ever written: "Supercalifragilisticexpialidocious," "Feed the Birds," "Jolly Holiday," "Spoonful of Sugar," and "Chim-Chim Cher-ee."
It was Disney's Schumacher who broke the ice by approaching Mackintosh on his own to work out a co-production agreement.
When the show opened in London in 2004, Mackintosh's commitment to Travers was apparent in some scenes that critics described as dark -- including one scene reminiscent of "The Nutcracker," in which the children lose their tempers in the nursery and are frightened by their toys.
"It's something that shocks them into realizing what their bad behavior actually is doing," Mackintosh said. "And it's a very good lesson. And that's what Mary Poppins is there to teach them."
Disney has never shied away from such moments, said Schumacher.
"We tell fairy tales like 'Beauty and the Beast' where people get turned into monsters and thrown off parapets," he said. "We tell stories like 'Lion King,' which is the crisis of a boy and what happens when his father is killed in a horrible stampede, which we watch on stage. And then we see him recover from that. And then I think of 'Mary Poppins,' which is the story of a family that's completely disjointed. What they do is, they find out that a nanny can set them all straight, and they can be a happy family at the end. I don't get what about that would be dark."
Audiences familiar with the major songs from the film will hear them all, presented in ways that are tailored for a theatrical production.
The team of George Stiles and Anthony Drewe was hired to work with the original Disney songwriters, Richard and Bob Sherman, to create new material and put some surprises into the standards.
One of the new songs, a number in which Mary Poppins introduces herself as "Practically Perfect," has been mistaken by some as having originally appeared in the movie.
Richard Sherman's reaction was also positive: "I said, 'That's one of the best songs I never wrote.'"
As one of the original writers, Sherman, too, has his Pamela Travers stories. He said she had trouble understanding why he was writing new music.
"She suggested 'Greensleeves' and 'Pop Goes the Weasel,' and 'Ta-Ra-Ra-Boom-De-Ay' as songs that Mary Poppins would sing. And I had to explain to her one day, 'Mrs. Travers, this is an original musical, and people already know 'Greensleeves' and we're going to try to do new material for this picture,'" he said.
The songs the Shermans produced "are part of our musical DNA," Drewe said. "We know all those songs without necessarily knowing where we were when we first heard them. You absorb them by osmosis. And our job was to write in that style."
For instance, the song "Jolly Holiday" now has a counterpoint melody written by Stiles and Drewe in which the children disdain what Mary is teaching them until the lesson unfolds and they are amazed, instead.
Arguably the most famous song from the film, "Supercalifragilisticexpialidocious," lasted less than two minutes. On the stage, it has been turned into an extravaganza that includes a clever, choreographed lesson in how to spell it.