When Gary Oldman learned that he would be playing world-weary British spy George Smiley, he knew the best research would be to ask a real spy what the Cold War was like. The man he asked spent six years, from 1958 to 1964, tapping phone lines, stealing information and running secret agents for both MI5 and MI6. He was David Cornwell, better known as John le Carré.

‘Britain has always had spies and I think we’ve spied rather well,’ says Oldman, 53. ‘But we have a rather romantic view of it and le Carré was the first to really show the reality.