Lily James pats her inner Meryl to become a dancing queen

What does it make to shoot a musical where the songs are huge hits?

The first thing I did was go to Stockholm and record my songs with Benny [Andersson] and Bjorn [Ulvaeus] The Benny workshop and I were singing Abba songs in front of Abba.

And Anthony Van Laast is the choreographer and he's just the best – a magician of the movement. At first I thought to myself, "No, I do not want to be told what to do, I need to be an actor where you should just understand." I slowly began to realize that following this fairly rigid structure allowed complete freedom in music and performance.

How do you prepare to play Meryl? Streep?

[Deep inhale and exhale] Well, I tried to be really proactive about this, just to show that I had done all the work I could. And I watched the movie thousands and thousands of times and tried to imitate his ways and capture what I thought about the essence of Donna and what Meryl did. I believe a lot because of the nature of the film. But she seems really rooted, cool and generous. But you know, she's Meryl Streep, so she walks into a room and it's amazing. She was singing in that chapel and I knew that I was about to meet her, and I started crying. It was just too much to make me dizzy. And I told myself to do it together. She is my favorite actress

Then Dear.

It was wild. I brought my mother on the day Cher was singing. And me and my mother had this amazing picture of watching the monitors in a dark corner of Pinewood [Studios, near London] just shaking. It was very surreal, this intimate, private and intimate concert of Cher. His voice is so extraordinarily powerful and rich, and when you hear it in the flesh, it is hypnotizing.

Do you have a favorite scene?

There is a moment when I meet Bill, the young Stellan Skarsgard character played by Josh Dylan, and we dance on the boat on the way to Kalokairi. And there was this magical week where every day we were in the Adriatic Sea [in Croatia] that sparkled, danced on this beautiful boat and Abba was screaming and it was too good to be true. Every day we had to jump into the sea and the sun was setting when we went home. That's what I think is so special about [the movie]. If it's your cup of tea, it's just merry.