Cressida Bonas is ''paralysingly'' shy.

The 26-year-old actress - who previously dated Prince Harry for two years - admits she finds it hard to comprehend why she doesn't have more confidence in her daily life because when she acts in theatre or in a film she has an abundance of self-belief.

Speaking to Miss Vogue magazine, she said: ''I don't really understand it; in real life I'm often so shy - paralysingly so, but when I'm performing, it's totally different. I feel free.''

Cressida is set to star alongside Dame Judie Dench, Christoph Waltz and Cara Delevingne in Harvey Weinstein's upcoming film 'Tulip Fever' - in which she will play Mrs. Steen, a merchant's society wife - and the director believes this part will be a catalyst for the beauty's movie career.

He said: ''People will see what a fantastic actress she is ... It will be the first of many roles for her.''

Earlier this year, Cressida was said to be in talks to appear in TV period drama 'Downton Abbey' and has met creator Julian Fellowes to discuss a part in the programme.

A source said: ''Cressida is trying to break into Hollywood and knows a Downton role would do wonders for her profile, not only in the UK but also the US.

''She met Julian in the run-up to the Golden Globes.

''While it was a very informal chat, Julian was said to be hugely impressed with her.

''He even promised to set up a meeting with the show's casting director in the UK to talk about a possible cameo in the next season, which may lead to a more permanent role.''