PLAYING the Queen would be pressure enough for any actress, but it came with additional stress for Sarah Gadon, who stars as a young Elizabeth II in new film A Royal Night Out.

"After I learned I had the role, I flew to London to meet Julian [Jarrold, the director], and he looked at me midway through our first meeting and said, 'You're so Canadian!'" says the 28-year-old, who was born and still lives in Toronto.

"I saw the terror in his face!" she adds, laughing. "I bounced in, in my Canada Goose jacket and I was talking about things in my accent, and he just kind of freaked out. At that point, I thought, 'OK, I've got a lot of work to do'."

That work included learning more about the Queen's early life and personality, how she got involved with efforts on the home front during the war, as a mechanic and driver.

"I was constantly inspired by the strength of her character," says Gadon, between aptly ladylike sips of tea - from a cup and saucer, naturally.

"I read that the children were taught that if you fall, you do not make a face. You were not supposed to show your emotions. You were not to allow your emotions to rule your decisions, or your feelings or your preference.

"And that's another thing; the Queen is not allowed to have preference... so interesting."

But for one night only, Her Majesty, then a 19-year-old princess, and her sister Margaret, slipped out without pomp and ceremony to join the VE Day celebrations, partying with the people before reportedly returning to Buckingham Palace just after midnight.

While the film touches on this outing, there's also a fictional romantic liaison with a Tommy thrown into the mix, and imagined jollities for Elizabeth and her younger sibling, played by Bel Powley.

Though Gadon's own upbringing, in an "artistic environment" ,was admittedly the "antithesis" of the Queen's, she found some common ground.

"I've always been determined to be an actor," she says. "I really felt my determination and sureness of my path was in common with Elizabeth's. She always had that sense of duty and wanted to please her parents and fulfil her destiny, and I feel like I've always felt that way too."

Gadon, who says she became a huge fan of Marks & Spencer's soup range while she was filming in Hull and London, had her first taste of performing as a schoolgirl, enrolling at Canada's National Ballet School when she was six, and soon landing a role in a production of The Nutcracker.

She started winning small roles in Canadian TV series in the late Nineties, before making her big screen breakthrough in period movie Belle, alongside Matthew Goode and Emily Watson, last year.

Her parents' reaction to seeing the movie ("They loved it!") at the Toronto International Film Festival was, she says, one of her proudest moments so far. They're thrilled about A Royal Night Out, too.

"My Nana was in the Women's Auxiliary Air Force in World War Two," explains Gadon of her late grandmother. "I had a very close relationship to her, growing up.

"I saw so much of my grandparents in this story, in this moment in time that they were both very much a part of. It was really special for me.

"My father and uncle had always said, initially, that my Nana wanted to drive Jeeps and be a mechanic in the war," the actress continues. "But when she'd done her psychological testing, they decided to put her to work with the War Rooms, which was obviously a great honour.

"When I was doing my own research, I thought, 'I wonder if she had wanted to do that [drive Jeeps] because Elizabeth had done it'. Seeing Elizabeth's influence on my own grandmother in that way, made me see how she influenced women of that time."

As for her own idols, Gadon looks up to Julianne Moore, who she worked with in dark drama Maps To The Stars last year.

"Julianne Moore is an incredible actress, very dedicated, fearless and she's run the spectrum of film-making," she says.

"She's also a very down-to-earth person, very grounded in who she is. I really grew to admire her while I was working with her. She's the real deal."

Gadon also had the enviable task of working with Breaking Bad actor Aaron Paul and 50 Shades Of Grey star Jamie Dornan, in thriller The 9th Life Of Louis Drax, due out later this year.

"Jamie's a real family man," says the rising star, who says she hasn't seen the "lovely" Dornan in 50 Shades yet.

"His family was with him while he was working, and for me, that was a big inspiration, to see a family working and travelling [together]."

And despite the upheaval so often involved, and the uncertainty of whether or not jobs will keep coming her way, she's sold on her career path.

"I remember when I was at school, having that exhilarating feeling of stepping onto a stage and looking on to the darkness, into the black abyss, and then feeling that joy of performing," says Gadon.

"I loved every part of it, and I loved being part of it. I'm so lucky to do what I do."

A Royal Night Out is released on Friday, May 15