Super Emily always sounds precocious

Emily Blunt's Mary Poppins is a "weird amalgamation" of Rosalind Russell in "His Girl Friday" and Princess Margaret. Photo / Supplied

Emily Blunt loves a challenge, and in the world of movie musicals there's no greater trial than following in the footsteps of Julie Andrews to bring one of her most iconic, and beloved, roles to the screen for the first time in over half a century.

It's only Mary Poppins. No pressure, right?

But the 35-year-old British actress has always been drawn to roles that scare her, and it's proven to be a good strategy. Some of her most memorable parts have been those "impossible" ones, like stealing scenes from Meryl Streep in The Devil Wears Prada and doing stunts with Tom Cruise in The Edge of Tomorrow.

There's no one type of Emily Blunt role, but some roles seem like they could only be for her, and for director and choreographer Rob Marshall, the practically perfect nanny was one of them. When he signed on for Mary Poppins Returns, which would be a sequel to the 1964 classic, hers was the first name he thought of.

"It was the quickest, fastest idea. I knew in one second who it was," said Marshall. "She had all the requirements."

He knew how big an ask it was ("It's the climbing of Mount Everest," he said), but he also knew from directing her in Stephen Sondheim's Into the Woods that she was right for the job. "She's so fearless," he added. "I just knew that she would make it her own."

I just had the sort of lasting impact of the joy bomb that the original was.

Emily Blunt

And Blunt said yes to Marshall in a single conversation. "I knew I had my work cut out for me just because of how extraordinary the original was and how beautiful Julie was in the original. But I knew that if I was going to take a big swing and carve out new space for myself, if I do it under Rob's guidance, I'd be all right," Blunt said. "He's kind of a magician. He's a bit of a Mary Poppins himself."

She was able to take a year, during which she was "massively" pregnant with her second child, before they started rehearsing and filming to figure out her interpretation of the character with the help of P.L. Travers' books.

"She is very different in the books," Blunt said. "She is completely batty and funny and vain and rude and terribly empathetic in a very weird way, not necessarily by what she says but by what she does."

Although she held fond memories of Andrews' performance, she hadn't revisited it as an adult and decided not to before filming.

"I didn't have any of the details of what she did with the character in my head. I just had the sort of lasting impact of the joy bomb that the original was," she said. "That was very helpful. I just read the books."

For Blunt, who delights in altering her voice and physicality for every role, her Mary Poppins was going to be "a weird amalgamation" of Rosalind Russell in His Girl Friday and Princess Margaret.

It's also capping a big year for Blunt and her husband, John Krasinski, which started with the unexpected success of A Quiet Place and is ending not only with the release of Mary Poppins Returns, but awards buzz and nominations for both films as well. This week she picked up Screen Actors' Guild nominations for both films.

The film finds the now-grown Banks children Michael (Ben Whishaw) and Jane (Emily Mortimer) faced with their own troubles, and Mary Poppins steps in to help care for Michael's three children and get their lives back on track.