Katy Manning, who starred in the science fiction series with Jon Pertwee in the 1970s, said it had been forgotten that second doctor Patrick Troughton was not well known when he was cast in the show.

She said: “I think somebody who is lesser known is a fabulous idea … I think it’s a great idea because it gives you a wonderful canvas to accept the truth of this man. Plus, why does he have to be old?

“This guy, to me, has this gothic feel. Jon had that ethereal quality; he could be 2,000 years old but you could also see the young one in him.

“I’m just using him as an example. I think it’s a fabulous idea to have somebody of this age who has that darker side. I’m very excited.”

Mr Smith, from Great Billing, was announced for the role in January and will take over from current doctor David Tennant.