Claire Foy admits her anxiety ''exploded'' when she became a star.

The Emmy-winning actress - who starred as Queen Elizabeth II in the Netflix series 'The Crown' - has been dealing with anxiety for years, but her situation worsened once she found stardom.

She explained: ''When you have anxiety, you have anxiety about - I don't know - crossing the road.

''The thing about it is, it's not related to anything that would seem logical. It's purely about that feeling in the pit of your stomach, and the feeling that you can't, because you're 'this' or you're 'that'. It's my mind working at a thousand beats a second, and running away with a thought.''

Asked about the specific thoughts she was dealing with, Claire admitted: ''It's lots of thoughts about how s**t I am.''

Claire, 34, found that her problems deepened because of the career path she decided to pursue.

She told the Guardian newspaper: ''It definitely magnified when I started doing this. Exploded. Yeah.''

Although 'The Crown' has helped Claire to become one of the most well-known actresses in the world, she was initially reluctant to commit to the project.

However, the British star - who has a three-year-old daughter called Ivy Rose with actor Stephen Campbell Moore - welcomed the financial security the show offered her.

She said: ''I was reticent - I've always been reticent about bigness. And I was scared, I didn't know how I'd be after coming out the other end of having a child.

''You just don't know - something could happen, I could get postnatal depression, I could, I don't know, develop a limp? So many variables!

''But I said yes to it. I knew it would be financially stable. We needed to buy a house.''