Helen Mirren insists her portrayal of Elizabeth II in The Queen is full of respect for the monarch.

Royalists have been concerned that the docu-drama, which follows the queen and her family in the period after Princess Diana's death, would portray her majesty in a bad light. Their worries were fuelled when they heard it would see her swigging gin and tonics, preparing for bed and being called "cabbage" by Prince Phillip.

Mirren, however, insists she has a huge respect for the monarch which is carried in her performance and into the film. "I wouldn't have done it if I had felt the film betrayed [The Queen]," she explained. "It's very easy to take cheap shots at people and be cruel and venal and lie about them.

"If I'd felt the script was in that direction, I wouldn't have done it, but I felt it was sensitive, funny and human." The actress, who spent months studying books and footage of Elizabeth, described her interpretation of the woman. "She's not vain. I don't think she has any interest in what she's wearing.

"I think they lay her clothes out and she doesn't even look at them. I bet she never even looks in the mirror, maybe once to see if her hat is on straight," she said, and recalled the one time the two had met. "She was immediately engaging because she was charming, twinkly and funny.

"I believe in nobility of character and that certain people have it," Mirren continued. "It doesn't matter what class they come from. I think the Queen has it. If she had been a housewife or a working-class woman, her intrinsic character is quite noble. I do believe that."

The Queen is in cinemas from 15 September.