So this is how we arrive at Last Christmas. It's set in a bleak, futuristic landscape covered in the ubiquitous Christmassy snow. Shaun of the Dead star Nick Frost is playing Santa Claus – the real Santa Claus, although that doesn't exempt him from the Doctor's withering looks. In fact, it’s the first time in the TV programme’s 51 years that the Doctor and Santa have come face to face. And, amid persistent rumours of her departure, Coleman is back for now. What we don't yet know is if she will be leaving on Christmas Day or if we'll be seeing more of her in 2015.