He told Crave: “We’ve sort of got to the point, especially if you’re a fan, you sort of think you’ve made a list and you’ve got everything. And you look at it and think okay, you think you know everything about the Doctor? What’s his name? Who is he married to? Who were his children? Did he have any other grandchildren? What was his job? You know nothing about the Doctor… So occasionally we have to remind the audience.
“He could be lying to you. He is so reticent on information, he hasn’t introduced himself in 50 years. So I had that idea [of Hurt's Doctor] kicking around for a while to shock everybody and say this man, who is defined by the secrets he keeps, has got a big one.”
He adds: “If you’re going to introduce a new Doctor from his past, it’s got to be a screen legend. Whoever turns around, you’ve got to go, ‘Wow! That’s amazing that they’re the Doctor!’ It can’t just be some bloke.”