From an interview with Svetlana Khodchenkova who plays Irina in Tinker Tailor (translation from Russian by google + me):
Your partner in the film was Tom Hardy, who in his native Britain is being called the new Marlon Brando. What was it like to work with him?
- Oh, immediately there were rumours of a romance with Tom. Initially I was upset, but then I thought: “Let them write.” Nothing happened, of course - we became friends on the set, nothing more.
Hardy is a real chameleon, a master of transformation. When we met, he was in makeup. He’s blue-eyed and blond in the movie, and wears expensive suits. So I thought that he looked the same in real life. Two days later I go to the dressing room, and there is some kind of brutal kid. Bald and huge, looks like a rapper. I was confused: “What is this? Who is this?" He turns around, and with difficulty, I realise it’s Hardy.