Dame Maggie Smith still finds acting "scary".
The 'Harry Potter' actress - who is said to be a "difficult" person to work with - insists her rumoured frosty nature is because she is still so nervous about doing her job.
She said: "Oh, I know, I keep hearing that. Obviously at some times I have been like that - the awful thing is, I'm sort of very aware when I'm being difficult but I'm usually ... so scared ... And that's shaming, at the age one is.
"Because every time I start anything, I think, 'This time I'm going to be like Jude [Dench], and it will all be lovely, it will be merry and bright, the Quaker will come out in me.' But it never works. Jude has a wonderful calm, it's very enviable. I think it would be hairy if she let fly, but I've never seen that."
However, the 80-year-old star insists she has no plans to change as it would "frighten" people more if she was nice.
She added to the Daily Telegraph newspaper: "But it's gone too far now, to take back. If I suddenly came on like Pollyanna, it wouldn't work - it would frighten people more if I were nice. They'd be paralysed with fear. And wonder what I was up to.
"But perhaps I should try it ... 'Hello! What fun! We're going to be here all day! And then filming all night too! Goody! And it's so lovely and cold!'"