Matt Smith was not the only one wearing a wig in the Doctor Who Christmas special as writer Steven Moffat revealed Karen Gillan also wore a hairpiece for her return.

The Scottish actress made a brief appearance as Amy Pond at the end of the episode as viewers saw Matt bow out as the Time Lord and hand over the controls of the TARDIS to Peter Capaldi.

Matt had to wear a wig after having his head shaved for his role in Ryan Gosling’s film How to Catch a Monster, while Karen had her hair cut off for the Marvel sci-fi film Guardians of the Galaxy.

Steven said: “They’re very good wigs, but they’re both wigs. Though in Karen’s case that’s her own hair. That wig is made of her own hair, it’s just detachable now.

“When they cut her hair they made her a wig of her own hair. Didn’t she look lovely?”

He said he had no hesitation in bringing Karen back for Matt’s last episode, saying the pair were ‘so iconic’.

“It was just nice to bring her back, also I just thought it would be good for Matt to have her on set.”

Steven said Matt’s ‘heartfelt, brilliant and ancient’ performance as an ageing Doctor was perfect, saying: “It’s an end of an era, he should talk that way. You need a combination of huge sadness and lucky it doesn’t end here.”