The Shutter Island star and her American husband Alessandro Nivola switched citizenship in 2010 - but she insists it had very little to do with patriotism.
And she's still upset about how difficult it was for her to become an American.
She says, "I kept saying, 'I don't want to do this that badly; why are you acting like it's such a big thing?' It was a year of just endless questioning. I had to learn 100 questions about the constitution and I had to have all sorts of medical probes and tests.
"I had to show photographs of my wedding, I had to talk about how much I loved my husband, which was very easy of course. It was endless and I b**ched and moaned the whole way through the whole thing.
"My husband, meanwhile, all he had to do was pay 400 quid (pounds) and say 'God save the Queen' - and he got a British passport."