Dame Helen Mirren reveals she wrote to Queen Elizabeth II warning her about The Queen film

Dame Helen Mirren has revealed she wrote to Queen Elizabeth II to warn her she would be portraying her in a movie during a "profoundly painful" time in her life.

The 2006 drama The Queen - which was written by The Crown creator Peter Morgan - focused on the death of Princess Diana and whether Her Majesty would return to London from Balmoral to pay tribute after she was criticised for her reaction to the 1997 car accident.

The 76-year-old actress, who won an Oscar and BAFTA for her portrayal, said she had quickly realised she was dealing with a sensitive moment in the Queen's life and decided to contact her.

Speaking to Radio Times, she said: "I realised we were investigating a profoundly painful part of her life, so I wrote to her. How do you write to your Queen? Was it 'Madam,' or 'Your Highness,' or 'Your Majesty'?

"I said, 'We are doing this film. We are investigating a very difficult time in your life. I hope it's not too awful for you.'"

She added: "I can't remember how I put it. I just said that in my research I found myself with a growing respect for her, and I just wanted to say that."

Mirren also revealed received a reply from Buckingham Palace.

She said: "She didn't write back, of course, but her secretary did. You know, 'Yours sincerely, da di da di da,' on behalf of the Queen. I was very relieved subsequently that I had written that letter."

Following the release of the film, she was invited to have dinner with the monarch but was unable to attend because she was filming in the US.