Du play the young composer Robert Frobisher in your main storyline. Did Du have to study music?

Ben Whishaw: Tom [Tykwer] phoned me three months before we were going to shoot and said, “You need to have Piano lessons.” So he sent me the score and I found a teacher in London. Miao-miao, her name was. I learned a lot about Frobisher that way.

Which was the most liberating character to play?

BW: I liked being the woman [Whishaw plays Hugh Grant’s wife in the modern-day storyline]. It was only one day’s filming. We did this whole experiment with lots of prosthetics and creases and wrinkles...