Homeland star David Harewood was left feeling "unnerved" after a lunch meeting with a real-life CIA agent turned into a fully-fledged interrogation.

The actor talked to a female secret agent to research his role as Central Intelligence Agency boss David Estes in the hit TV drama, but admits he failed to keep his cool and ended up telling her all his secrets.

He recalls, "It was supposed to be me pumping her for information. Instead, I suspect I told her far more about myself than I wanted to - or realized I was doing. If I'd been a terrorist, she would have had a confession out of me wi...