By Caroline Briggs
Entertainment reporter, BBC News
Dame Helen Mirren won the best actress award at the Venice Film Festival for The Queen, which has its UK premiere on Wednesday. She talks about her transformation from acting royalty to British monarch.
Mirren's portrayal of The Queen has been widely praised
Playing the Queen is something Dame Helen Mirren admits she was initially nervous at the thought of tackling.
"I was terrified at the thought of doing a film about the monarchy and the dangerous, turbulent waters that one might stray into," she tells the BBC News website.
"I considered what the Queen might think before I started working on it. I felt an honest effort was essential, that's all you can do."
Directed by Stephen Frears, The Queen examines the Royal family's reaction to the death of Princess Diana in a Paris car crash in 1997.
It swings from the peaceful beauty of Balmoral, where the family were firmly ensconced, to the centre of London where public feeling against the monarchy was growing uglier by the day.
Transforming herself into the Queen for the role was an emotional and physical feat, Dame Helen explains.
She watched hours of footage and underwent voice coaching to capture the monarch's distinctive mannerisms and clipped tones.
"I watched tapes, read books, I looked at portraits, but the most valuable for me was looking at the Queen as a young girl.
"There was a tiny 20 seconds of film of the Queen at about 12-years-old getting out of a car and putting her hand out to shake hands with someone.
"The way she gets out of the car and the way she puts her hand out, to me, absolutely encapsulates who the real person is when you extricate her from the institution.
"I watched that bit of film over, and over, and over again and when I played her I was always playing that little 12-year-old girl."
'A woman without vanity'
It was a tenacious approach that paid off for Dame Helen.
As well as winning the best actress Golden Lion, critics are widely tipping her convincing portrayal of the Queen for an Oscar nomination.
Prince Philip is played by James Cromwell
While Mirren insists she does not share any similarities with the Queen, she admits to feeling "comfortable" in the monarch's skin.
"When I did the costume fitting I cried. I thought I can't wear those horrible ugly shoes, and those horrible tweed skirts. I can't be this dowdy person, I can't go there.
"But when I did, when I got myself in there, I found that I absolutely loved it.
"She is a woman without vanity, and I think that was a relaxing place to be."
Above all, Dame Helen was determined to stay true to the Queen, often reining in Frears when it came to filming the more emotional scenes.
But she is keen to stress she does not think the monarch is simply a "stoic shell".
"It's very interesting looking physically at the Queen. She's so contained, and calm, and everything is in its place and perfect, and when you look closely there is always something moving, usually her finger, or playing with her wedding ring.
"She looks utterly composed but then you see her hands going around and around and around.
"There are these little clues of an inner energy or emotion or something."
Mirren said she was 'honoured' to win the best actress award at Venice
The Queen is Dame Helen's latest incarnation in a career which has firmly established her as acting royalty.
After starting out in the theatre, including a stint with the Royal Shakespeare Company, Dame Helen began her film career in the late 1960s in Michael Powell's Age of Consent.
Her breakthrough role came in 1980 when she played the tough but sexy mistress of Bob Hoskins' volatile cockney gangster in The Long Good Friday.
More recently she has starred in films such as Calendar Girls, Gosford Park and The Clearing, alongside Robert Redford, garnering two Oscar nominations along the way.
Her TV work has included the mini-series Elizabeth I, for which she won an Emmy, and she will also back in the seventh series of ITV1's Prime Suspect, playing tough-as-nails cop Jane Tennison, in October.
"I'd love to see the Queen play Jane Tennison," laughs Dame Helen, comparing her role as the Detective Chief Superintendent with that of the British monarch.
But she admits her detective work fails when it comes to knowing what the Queen thinks of Dame Helen's portrayal of her.
"The question that everyone wants to know is 'what do you think the Queen will make of it?'. I don't know, I have no idea. It's not my place to know.
"I suspect - and when the great royal writer Robert Lacey was asked the same question he said just this - I think the Queen would say, 'Well that could have been worse. Could I have a gin and tonic please?'"