This week’s episode of Doctor Who contained a special treat for fans of the classic series, with 1970s alien character Alpha Centauri (a hermaphroditic hexapod ambassador with one big eye) returning for a surprise cameo at the end of the episode.

And now in a new video series showrunner Steven Moffat, episode writer Mark Gatiss and star Peter Capaldi have revealed the thought process behind Alpha Centauri’s return, as well as their decision to bring back original voice actress Ysanne Churchman to reprise her role.

“I can’t believe I’ve got away with this! I was convinced it would, literally the first draft they’d go ‘We’re not doing that,” Gatiss recalled. “But now it’s happening and I can’t quite believe it.

“Curse of Peladon is one of my all-time favourite stories. I have such fond memories of it. And I love the boldness of the hermaphrodite hexapod. It’s a marvellous thing, a little nod to the past.”

“She gripped the nation,” Moffat added. “Everyone was talking about the hilarity and the glory of this mad alien.

“And here we are, we’re going back to Alpha Centauri and seeing that again. Mark was very very keen to recreate that moment and to get the original actress in the create the voice of Alpha Centauri.”

“If wouldn’t have mattered terribly to the story if we weren’t able to get the original actress who played that part,” Peter Capaldi said. “But it’s nice that we did.

“It’s a good thing about the show. It’s fun! And you know, for those who remember her original performance, it’s lovely to know she’s still connected to the show. Gives it an extra little kick for those of us who saw it first time around.”

Doctor Who continues on BBC1 this Saturday 17^th June at 6.45pm