The 34-year-old Oscar-winning actor played William Stafford, the husband of Scarlett Johansson's Mary Boleyn, reported Digital Spy.
"I don't know how I got cast, but it was the opportunity to work with Scarlett, Natalie (Portman) and Mark (Rylance), so I definitely wasn't going to say no.
"Everyone was looking at me going, 'Why did they cast him?' I have no idea! I have no idea why they cast me, but I'm just going to sit here with my hat on and my big outfit," Redmayne said.