And then there's this guy... British mum, American dad. Born in the USA, but just before his first birthday came back to the UK with his mum. Hasn't left the country since. Is now 58 years old. And has to take a Citizenship Test. Apparently to take the test, you get a book called Life In The UK, read it, and then sit a 45-minute written test. Here is some information about the sort of thing they're concerned with.