She was the nanny sent from above to save wayward children and parents alike. A woman who was practically perfect in every way.
But while Mary Poppins went on to become one of the most beloved children's films of the 20th Century, filming the popular tale was a far-from-happy experience, reports The Sun.
Julie Andrews won her first Oscar in 1965 for playing the prim-and-proper Poppins - but the actress reportedly had mixed feelings about the role, which left her typecast for the rest of her career.
According to The Sun, the actress once stuck a bumper sticker to her car that read: "Mary Poppins is a junkie."
On screen, Julie Andrews and her co-star Dick Van Dyke were all sunshine and light, playing the beloved nanny Mary Poppins and chimney sweep Bert. But off-screen, things were much darker.
Andrews reportedly stunned her fellow cast members - including the young actors who played her charges Michael and Jane - with her frequent swearing and smoking on set.
Meanwhile, Van Dyke struggled with serious depression during shooting, telling The Sun he had suicidal thoughts while performing the famously upbeat role.
Karen Dotrice, who played eight-year-old Jane Banks in the 1964 film, told The Sun: "There was swearing. Julie Andrews was smoking on set. It was a very real 1960s set, I can tell you. They were polite around minors to begin with, but that soon ended."
Van Dyke - who makes a cameo appearance in Disney's new reboot of the film Mary Poppins Returns - admits he struggled with alcoholism and depression at the time of filming the original.
"I would go to work with terrible hangovers, which if you're dancing is really hard," he told The Sun.
The 92-year-old added: "I was in deep trouble, you get suicidal and think you just can't go on."
Behind-the-scenes, there was more drama as the author and creator of Mary Poppins waged war against Walt Disney - a tale captured in the sugar-coated 2013 film Saving Mr Banks.
According to Van Dyke, PL Travers hated both him and Julie Andrews. She also disapproved of the final film and refused to allow Disney to make a sequel, stating in her will that "no Americans shall ever be granted permission to work on a Poppins project ever again".
Travers died in 1996. Her estate has since given Disney permission to release a sequel, which opens in cinemas on New Year's Day.