Dame Helen Mirren finds starting a new job to be a "nerve-racking" experience

She told People: "I think it's because every project that you go into is an unknown.

"And each time you enter into a new project, you never know how it's going to be or how the people are going to be and whether the chemistry will be good or a disaster. So stepping into a project is nerve-racking."

Helen acknowledges that every role is a new and unique challenge.

The veteran actress explained: "Every single one is completely different and has a different energy and a different requirement, you never know if you're going to sort of step up or not."

And despite her past successes, Helen still finds herself feeling "insecure".

She shared: "A lot of it is pretense, of course, sort of acting. You feel insecure, but you pretend you don't. And we all do it, don't we?

"Walking into a party or walking into a job interview or whatever it is you're having to deal with. We all have sort of gird our loins for want of a better word."

Meanwhile, Helen recently suggested that she could have been a competitive racing driver.

The award-winning actress is "foolishly vain" about her skills behind the wheel and is convinced that if she hadn't had such a successful screen career, she'd have done just as well on the race track.

She told People: "I'm rather foolishly vain about my driving. I'm sure I could have been a racing car driver."

Although Helen - who is married to director Taylor Hackford - turned 80 last month, she doesn't "recognise" birthdays because "life rolls on" and she isn't interested in extravagant celebrations.

The film star said: "Honestly, I don't celebrate birthdays. I don't recognise them because life just rolls on.

"I expect to be very, very nicely treated on my birthday. That's all I want. Cup of tea in bed in the morning."