Carey Mulligan has insisted 'Maestro' isn't a Leonard Bernstein biopic.

The actress plays the composer's wide Felicia Montealegre opposite Bradley Cooper as Bernstein and she's declared the movie is actually more about the couple's marriage than the celebrated composer/conductor's rise to fame.

During an interview with Vogue magazine conducted before the start of the Hollywood actors strike, she explained: "I know people will talk about Maestro as a biopic, but not. It’s a movie about a marriage - a very complicated marriage."

The 38-year-old actress went on to reveal her preparations for the role was intense and included a "dream workshop" with her co-star and writer/director Cooper.

She told the publication: "This was the most intense preparation I’ve ever done for a film ... I guess Bradley’s been doing this kind of thing forever, using your dreams to connect your subconscious to the character’s, but it was new to me. But I had to go all in."

Cooper also spoke to the magazine before the strike, and added of his co-star: "I knew her ability. All I asked of her was to please do the prep with me; I said: ‘Will you go down this road where we’re basically going to bare our souls to each other?’ And she was like: ‘Okay, let’s do it, I’m game'."

It was previously revealed that Cooper endured a five-hour makeup process to transform into Bernstein.

Oscar-winning make-up artist Kazu Hiro explained how he and his team would spend all night applying the cosmetics so Cooper could be behind the camera in character. Hiro told an audience at the picture's New York Film Festival screening earlier this month: "The last stage, he had covered pretty much everywhere, the bodysuit and arms. That took over 5 hours. "The last stage, the whole time, our call time was 1 in the morning. "The other thing was he wanted makeup to be finished before the crew call, so he would appear as Lenny to set up the shoot and everything. That also kind of made our call time two hours earlier than normal, so that was quite tough." Hiro explained that the length of time Bradley spent in the makeup chair varied as they filmed scenes from across Bernstein's life. He said: "(We had to) keep adding because as he gets older, we had to add more elements. The younger stage was the nose and lips and chin and a wig. After the third stage, he started having cheek and neck (additions)."

Hiro's work sparked outcry as Cooper decided to wear a prosthetic nose in his portrayal of Bernstein, who was Jewish, and the make-up artist did not intend to cause offence. He said: "I wasn't expecting that to happen. I feel sorry that I hurt some people's feelings. "My goal was and Bradley's goal was to portray Lenny as authentic as possible. Lenny had a really iconic look that everybody knows - there's so many pictures out there because he's photogenic, too - such a great person and also inspired so many people. "So we wanted to respect the look too, on the inside. So that's why we did several different tests and went through lots of decisions and that was the outcome in the movie."