Dame Helen Mirren was terrified about playing Queen Elizabeth.

The actress - who was awarded a Best Actress Oscar in 2006 for her role as the monarch in 'The Queen' - claims she was ''very, very nervous'' about taking on the iconic role.

Helen told HELLO! magazine: ''She's an icon all over the world. Everybody knows what she looks and sounds like.

''I knew I had to get those things right, but I wanted to go beyond a simple impersonation. So yes, I was very, very nervous.''

Helen, 66 - who has received high praise for her roles in 'Calendar Girls', 'Gosford Park' and 'The Madness of King George' - has also confessed that the death of Princess Diana depicted in the film must have been very difficult for the royal family.

She commented: ''What business was it of mine? I can see they would have been conflicted, though, because as far as the royal family were concerned, Diana had presented a succession of difficult scenarios.

''And then her untimely death turned her into a martyr. So it must have been hard.''

It seems Elizabeth II herself was happy with Helen's performance.

Helen joked: ''She's never publically commented on it, but I know she didn't absolutely hate it because I have subsequently been invited to tea at Buckingham Palace.''

Helen is currently filming biopic 'Hitchcock' alongside Anthony Hopkins and Scarlett Johansson.