Kenneth Branagh Loved the ‘Joyfulness’ His Devil Wears Prada 2 Love Interest Meryl Streep Brought to Scenes (Exclusive)

Kenneth Branagh continues to shower Meryl Streep, his The Devil Wears Prada 2 costar and on-screen romantic partner, with high praise.

In the new sequel film, Branagh, 65, plays Stuart, the new husband of Streep’s Miranda Priestly. He opened up about their dynamic while at the film's premiere at Lincoln Center in New York City on April 20.

"Well, she was very, very prepared," said Branagh about Streep, 76, while speaking with 12-year-old Taylen Biggs, who hosted PEOPLE's coverage of the premiere of The Devil Wears Prada 2.

Branagh added, "She's really, really rigorous about what she does. But I think that what ... she didn't make it official, but what I took from her was a sense of real joyfulness and play in the scenes. So she knew everything. She was totally prepared, but then in the moment, she reacted to what happened and what you said and how you said it. So she was very prepared, but also very improvisational."

Branagh is best known for his roles in Oppenheimer, Belfast, Dunkirk and My Week with Marilyn, which earned him an Oscar nomination for Best Supporting Actor. He was also knighted by the late Queen Elizabeth in 2012.

Meanwhile, Streep's character, Miranda, was loosely based on Anna Wintour.

“I didn't know her at all because of my dissociation from fashion for the first movie,” Streep said on SiriusXM's Andy Cohen-hosted Front Row.

“I just wanted to create my own Miranda,” she added. “I wanted to have it be my own thing, and, ‘Who I would be if I were in charge?' ”

Streep eventually "got to know her over the last 20 years." When it came to the sequel, Wintour, 76, called the Mamma Mia! actress to ask "What's this going to be like?"

She told Wintour, “ ‘I think it's going to be good. You're not going to be worried.' And I still feel that way.”

Related Stories

How Meryl Streep Got Lady Gaga to Be in 'The Devil Wears Prada 2'

'The Devil Wears Prada 2' Is Here! Celebrate with 10 Fashion and Beauty Collabs Inspired by the Film

Along with Branagh and Streep, the film's cast stars Anne Hathaway, Emily Blunt, Stanley Tucci, Lucy Liu, Justin Theroux, B.J. Novak, Pauline Chalamet, Patrick Brammall, Caleb Hearon, Helen J. Shen and Conrad Ricamora.

"It's going to be highly entertaining," Liu, 57, told PEOPLE. "It's going to give you all the things, all the eye candy, and it's going to show that these characters have grown and changed."

Our new app is here! Free, fun and full of exclusives. Scan to download now!

"I think that's what people want to see. They want to know 20 years later what's different, because you don't want to get served the same thing," Liu added.

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from celebrity news to compelling human interest stories.

The Devil Wears Prada 2 is out now in theaters.