Kate Winslet on what question she'd like to have asked Lee Miller

It's this period of her life that is the main focus of the new film, but it is bookended by a framing device that sees an older version of Lee being interviewed about her experiences.

With that in mind, we wondered what Winslet herself might have asked Miller if she'd had the chance, and so we put that question to her during an exclusive interview with RadioTimes.com.

"There are so many things I think I'd want to ask her," she answered before honing in on one particular question.

"I think I would probably ask her, 'How did it really feel to get into Hitler's bath?'

"Because there's a very famous image of her that was taken by her friend Davy Sherman, who was a photographer for Life magazine at the time. And the two of them were kind of joined at the hip during the war, and they bribed their way into Hitler's apartment."

She continued: "Hitler had vanished at that point. He'd escaped to his bunker in Berlin. It was on the day of the liberation of Dachau, and Lee and Davy had been present in Dachau that morning. They were among the first people there, and they went to Munich, and she knew where his apartment was.

"There was another regiment already in there, pretty much having a party. And she realised that there was a bathroom, and she went in, and she turned on the tap, realised there was hot water. They hadn't touched hot water for six weeks. They hadn't washed, they hadn't even changed their clothes. So, of course, she got in the bath.

"And then she, of course, realised, OK, that's a scoop. Davy, get in here, take a photograph of me, and Davey also was photographed in the bath too. And I just think I would ask her, 'How did that really feel? Like, what was going through your mind?' She was spectacularly brave."

Director Ellen Kuras – who has been a longtime friend of Winslet's and previously collaborated with the actor when she was the cinematographer on Eternal Sunshine of the Spotless Mind – also found it difficult to choose one question.

"There's so many layers to Lee Miller's life," she said. "If I could talk to the actual Lee Miller, I would ask her questions about her work as a photographer, her early work as a surrealist, and then what she was feeling when she actually went on the battlefield... what made her decide that she wanted to look at what was behind the scenes, rather than showing the actual combat.

"I'm kind of interested in, what was the inspiration for that? And for her to talk about that, and also to talk about her fervent commitment to finding the truth and telling the truth, and how she felt about that at the end, when she came back. Ultimately, what that told her about her own life."

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Lee has been a long-time passion project for Winslet, who spent eight years developing the film, and she explained that the spark for the idea first came after she had bought a table at auction that had previously been in the home where Lee lived with many other surrealist artists – including Man Ray, Paul Éluard and Max Ernst.

"I knew who Lee Miller was, and I was familiar with a lot of her photographic work, but I was also very aware of how almost... not underrated, but unexplored the most significant decade of her life truly was," she said.

"She had always been viewed through the male gaze. She's written about as having been the former muse of Man Ray, ex cover girl, former model, these kind of slightly patronising, almost infantilising labels that were slapped on her, and that was connected to a sliver of her life in her 20s."

After buying the table, she started to ask herself why no one had yet made a film about Miller's life, and decided to take it upon herself to correct that.

"Cut to nine years later, and I now know probably why no one's made a film about Lee Miller!" she said.

"Because it was incredibly hard to really define that period of her life that we wanted to talk about that mattered to me the most, and I think that celebrates the phenomenal work she did in going as a woman to the front line, cutting through the red tape and documenting the atrocities of the Nazi regime for the female readers of Vogue.

"She just didn't believe in hiding the truth, and she would stop at nothing until she had found it."

Lee is now showing in UK cinemas.

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