Doctor Who Season 8
Peter Capaldi in Doctor Who Season 8.Doctor Who/Facebook

Doctor Who's 12th Doctor Peter Capaldi was certain that he would never get to take the Time Lord's Tardis for a spin!

The 56-year-old actor, who is set to debut as the New Doctor next month, admitted that he had given up hope of playing the Doctor, as he thought producers wanted to replace Matt Smith, 31, with another young Doctor.

Capaldi told Entertainment Weekly magazine: "I wouldn't have thought I would be the guy. I wouldn't have thought it would be me, because of my age. I would have thought they were automatically heading younger."

He then joked: "I'm technically too young for the part, because he's over 2,000"

The first of the Doctors, Christopher Eccleston, was 41 when he first appeared on the show, while his successor David Tennant was 34. Capaldi's immediate predecessor Matt Smith was just 26 when he was cast in the role, reported Entertainment Weekly.

However, the show's executive producer, Steven Moffat, spoke in Capaldi's defence.

He insisted that Peter isn't too old for the part because there's "no right age to be the Doctor".

He explained: "I did say, 'No, we probably won't end up with another quirky young man.' I didn't think there was any space around Matt to have another Doctor of that kind, because he sort of sums up what you could do with that. I very, very quickly - very quickly - just thought about Peter."

The 12th Doctor's first full episode, Deep Breath, is due to air on 23 August on BBC One.

Here is the teaser for Doctor Who Season 8.