Speaking to Digital Spy, the writer said: “She just had this amazing energy, she’s actually a couple of years older than Karen [Gillan] but she seems younger – she seems more of a teenager and bouncy. She’s fantastic.
“It’s really hard to take over from any companion that’s loved like Amy and Rory are, and she’s just going to be so different whilst still being a Doctor Who companion. It’s a very good choice from the producers.”
Speaking about her appearance in the Series 7 opener, Asylum Of The Daleks, he said: “I was amazed that it stayed secret, but thrilled that it did,” he revealed. “It was a very clever decision of Steven [Moffat]’s to tease in that way, because he’s given away absolutely nothing but created a lot of interest.”
Speaking about his latest Doctor Who episode, The Girl Who Waited, he said: “It got just incredible, incredible reviews, I don’t think Doctor Who fans liked me very much before that, because I was very young when I got the job and I think they thought I hadn’t really earned it.
“So I worked really hard to do something that would prove the point that I had the right to sit at that table, and then everyone just loved it and I couldn’t believe it. I was so overwhelmed.”
However, he refused to confirm if he would be writing a new Doctor Who episode for Series 7: Part 2.
“I can tell you there are some unconfirmed spots, but I can’t say anything more than that,” he stated.