River Song is Back in New Christmas Special Pic
Additional casting includes Greg Davies as King Hydroflax, Matt Lucas as Nardole.
Meanwhile, Moffat has been speaking to the Radio Times again and confirmed further details.
On why he decided to bring River back: “We’ve just lost Clara, so I didn’t want to go straight into a new companion. I’ll be honest, I brought River Song back in because I thought there was a possibility I’d never write it [Doctor Who] again so that’d be my goodbye.”
On how the pairing with Twelve works: “It’s strange because they’re now, in our human terms, the perfect couple. They’re both sexy older people. It’s always been slightly strange before with Matt Smith. Now, yeah, they could actually be married. It works.”
He also added: “If you’re a long term fan of the show you might be interested because there’s been a lot of talk about the Doctor and River’s glory years but we’ve never seen them. Here at last we see them as Mr and Mrs Who at the height of their powers. It’s great fun.”
On when in River’s life it takes place: “It doesn’t really matter, but for those who care it’s immediately after The Angels Take Manhattan . River’s just seen Matt Smith’s Doctor lose Amy and Rory, and obviously before The Name of the Doctor  because she’s dead in that.”