Julie Andrews talks about Mary Poppins which she agreed to day after she gave birth

Julie Andrews has shared little-known details about her iconic Mary Poppins character in a new interview with Good Morning America.

The 84-year-old sat down with Diane Sawyer and opened up about falling into depression after losing her singing voice in 1997 but feeling she had to maintain the gleeful appearance associated with her movie characters.

Much like the side of Andrews unknown to fans of the 1964 movie and 1965’s Sound of Music, she shared that the famous nanny wasn’t all she seemed.

Speaking about her then-husband Tony Walton’s costume designing talent, she revealed he created a secret wardrobe – featuring bold undergarments – as a nod to Poppins alter-ego.

Julie Andrews opens up about Mary Poppins and her personal life struggles behind the cheerful characters she played on screen, in a new interview that aired on GMA Thursday

Andrews said Mary Poppins had a 'wicked and naughty side' that only she and her husband knew about. She said: 'Underneath all the skirts there were other colors. And so when I kicked up my heels or when I moved - you just caught a flash'

Andrews said Mary Poppins had a ‘wicked and naughty side’ that only she and her husband knew about. She said: ‘Underneath all the skirts there were other colors. And so when I kicked up my heels or when I moved – you just caught a flash’

'I was very good at whistling,' Andrews told Sawyer, adding someone was on the floor manipulating the robin

‘I was very good at whistling,’ Andrews told Sawyer, adding someone was on the floor manipulating the robin

‘It was a great help to me,’ she said. ‘He was — well, is — incredibly talented. And he said, ‘I fancy that Mary Poppins has a secret life.’ Kind of quiet pleasure at being a little wicked and naughty.

‘Underneath all the skirts there were other colors. And so when I kicked up my heels or when I moved — you just caught a flash.’

Another details Poppins fans may not know is that Andrews – who sang for the king of England when she was just 12 years old – whistled the well-known bird tune as well as singing the popular Spoonful of Sugar.

‘I was very good at whistling,’ Andrews told Sawyer, adding someone was on the floor manipulating the robin.

Her creative input in the film didn’t end there – she claims she came up with Poppins’ famous right-angled feet.

Diane Sawyer's interview with the star delves into details contained in her memoir out October 15

Diane Sawyer’s interview with the star delves into details contained in her memoir out October 15

Andrews said he husband Tony Walton, who worked on the film, was 'a great help to me' and said he is 'incredibly talented'

Andrews said he husband Tony Walton, who worked on the film, was ‘a great help to me’ and said he is ‘incredibly talented’

Andrews said she came up with Poppins' footwork: 'The feet need to be turned out'

Andrews said she came up with Poppins’ footwork: ‘The feet need to be turned out’

The idea ran through her head while on set of the motion picture, which she got the call for the day after she gave birth while still in hospital, and during which she had to tell the book’s P.L. Travers that she was ‘feeling a bit groggy right now’.

‘The feet need to be turned out,’ she said. ‘I don’t know [why], but you don’t want droopy feet. They just sort of flapped about — and I thought, ‘If I just take off and try to walk as fast as I can, almost to be floating, it would make them have to run to keep up.”

She opens up more about her career and personal life in her new book Home Work: A Memoir of My Hollywood Years, written with help from her daughter Emma Walton Hamilton and out October 15.

She opens up more about her career and personal life in her new book Home Work: A Memoir of My Hollywood Years, written with help from her daughter

She opens up more about her career and personal life in her new book Home Work: A Memoir of My Hollywood Years, written with help from her daughter

Hamilton appears in the second installment of the interview due to air Friday and in a teaser clip, Andrews is seen stroking her daughter’s face as she opens up about the sad times that she largely kept behind the scenes.

‘I finally got enough courage after the first week to say, ‘I don’t understand why I’m weeping so much. I can’t seem to stop,” Andrews – who has previously spoken about suffering from depression after she lost her singing voice in 1997 – said.

It’s unclear what moment in her life she is addressing but Andrews has also spoken in the past about being lonely while traveling the world as a youngster, and growing up in a turbulent household due to alcoholism ‘and despair on my mum’s part’, she adds in the new interview.

At one point in the clip she appears emotional as she recalls using music to overcome tough times. Her second marriage was to Blake Edwards who died in 2010 due to pneumonia complications.

She adds in the cryptic clip that her sadness wasn’t easy to talk about due to her happy-go-lucky screen roles.

‘You know, you’re surrounded by the wagons. And suddenly the cavalry comes up over the hill in one of those westerns. And you weep for relief,’ Andrews old Sawyer.

‘Those lovely first movies were no help either,’ Andrews said laughing about her life, which had been geared toward a sort of perfectionism.

‘Mary Poppins, practically perfect in every way — and she wasn’t. So there you are.’

She call for Mary Poppins the day after she gave birth and while she was still in hospital. She told the book's P.L. Travers that she was 'feeling a bit groggy right now'

She call for Mary Poppins the day after she gave birth and while she was still in hospital. She told the book’s P.L. Travers that she was ‘feeling a bit groggy right now’

Her daughter Emma Walton Hamilton appears with her in Friday's interview installment which appears to feature more emotional moments

Her daughter Emma Walton Hamilton appears with her in Friday’s interview installment which appears to feature more emotional moments

Julie Andrews also speaks about her marriages during the interview. She poses with her late husband, American film director Blake Edwards in 1992. He died in 2010

Julie Andrews also speaks about her marriages during the interview. She poses with her late husband, American film director Blake Edwards in 1992. He died in 2010

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