13/11/2015 8:40 AM AEDT | Updated 15/07/2016 12:51 PM AEST

Doctor Who's Peter Capaldi On Why The Long-Running Show Is A Success

In the age of throwaway everything and tiny attention spans, how do you make a character on screen survive and more difficult yet -- remain relevant?

This is the challenge that now rests with Peter Capaldi, who plays the 12th incarnation of the lead character of Doctor Who, and who has taken it beyond 50 years on television.

And this is keeping in mind that when the Doctor first aired on Australian television in January 1965, being one of the first international adopters outside the UK, Robert Menzies was still PM, public swimming pools were not admitting indigenous people, and the Vietnam War was still raging.

“I think I would like to see the Doctor go back to his past and I think I’d like to see him meet his first self. I think they’d have an understanding,” Capaldi said.

Enter Capaldi. The Scottish actor was once most famous for his role as Malcolm Tucker, a foul-mouthed political adviser from the British show, The Thick Of It.

And his mouth was indeed foul.

"No, he's useless. He's absolutely useless. He's as useless as a marzipan dildo." -- Malcolm Tucker

So, to take on the role as Doctor Who, beloved by children worldwide for his whimsy and fantasy, was a departure.

“Sometimes I look around and think this is the greatest job in the world,” he told The Huffington Post Australia.

“It is scary because you are conscious of the respect you have, of how the show is to people and trying to make it good.

“We never rest with it. We don’t roll around just thinking, ‘We deserve to be here’. This is a great family experience.”

Doctor Who is the longest-running sci-fi show in TV history.

One of the technical ways the show has survived is the “regeneration” process, which allows the central character to change his face -- and producers to change lead actor.

“You can’t do this in a cop show with a central character people are riveted to. The fact you change the leading actor produces longevity.

“That’s technically how the show has been able to survive, but I don’t think that’s why it survives.

“It manages to engage viewers in a joyful wonder about the universe, and combine that with a melancholic streak of doom, as well as have rubber monster suits. That’s what we want so see.”

Deep in fandom circles, it’s well known that Capaldi has a long-running connection with the show.

As a teen, he applied to be the head of the Doctor Who fan club (he failed). After badgering the production staff, a BBC secretary wrote an internal note to the production staff, saying, “I wish the Daleks or someone would exterminate him”.

Capaldi appeared in a Doctor Who episode about the fall of Pompeii. And he also appeared in a story arc in spin-off show Torchwood.

So how did showrunner Steven Moffatt explain the three iterations of Capaldi in the Whoniverse?

Last week, the Doctor solved the mystery. He “chose” that face as a reminder to himself of his mission, that he saves people, as his character did in Pompeii.

Capaldi as Lucius Caecilius Iucundus in Pompeii, as Mr Frobisher in spin-off series Torchwood, and as The Doctor.

Next weekend, the actor is joining stars of the cast, as well as directors, writers and producers, to host the Doctor Who Festival in Australia.

“What’s fantastic is the show has been in Australia for so long, it’s part of the television history and background of Australian entertainment,” Capaldi said.

“That’s what struck me very fully, just how much it’s a weird feeling of coming home. To get such a great welcome, from people who are so familiar with the show and so pleased to see you.”

The festival will also host executive producer and writer Steven Moffat, former companion Billie Piper, the 7th Doctor Sylvester McCoy and writer Mark Gatiss.

Dan Starkey, who plays Sontaren warrior turned nurse Strax, will deliver a masterclass on what it takes to play a monster.

Superfans will be able to test their show knowledge of obscure Doctor Who facts in a fan challenge. Brush up with our list of obscure factoids for clever boys and girls who waited.

A visit to the production village will answer a curious question -- who on the set looks after the keys to Dr Who’s big blue box, the TARDIS.

And Capaldi hinted the TARDIS may be ready for a makeover in the next season.

“The TARDIS changes from Doctor to Doctor and we’ve changed some of it. The original TARDIS control panel was used all the way up to (4th Doctor) Tom Baker’s era. But it costs a lot of money, and it’s a thing with the show that we spent money effectively.

“I’ve retained the same TARDIS, but we may be getting to revisit that.”

Capaldi will appear at The Doctor Who Festival on November 21 and 21 in Sydney.