Last time we saw The Doctor, he was saving the world, keeping Rose from imploding and taking one for the team, by forcing a regeneration. David Tennant had just a moment to say Barcelona before the episode ended.

Thus, his first full length episode is this Christmas Special. Although, he isn’t really in it for a lot of the action, so perhaps it’s harsh to call this his first episode. He spends most of his time relegated to a bed, or the floor of his ship, and 90% of the episode sees him in pyjamas - even the fighting at the end. I am not a fan of the pyjamas.

The TARDIS bounces into London, with Jackie and Micky running in as soon as they hear it. The Doctor falls out, and the confusion over his changed face begins.

This seems old hat now that we’ve seen the Doctor change a second time, but it’s easy to forget that this was the first time that new Who viewers would have seen a changed Doctor, and their fears must have been just as acute as Rose and Jackie’s.

Unconscious and still finishing his regeneration cycle, the Doctor is propped up in bed, where he looks very uncomfortable. He’s aware enough to come to the rescue when he needs to, but it’s not until a dropped flask at the end, the aroma of sweet tea and burning electrics, that he comes round.

In terms of the story, Harriet Jones is in charge, and it’s good to see a friendly face (to begin with), as Rose and Mickey face off blood-controlling aliens without any help from their hero. The early moments of the story have echoes of Steven Moffatt, with terrifying Father Christmas fakes, and whirling Christmas trees - childhood things that become scary and could cause nightmares.

Some of my favourite snippets were Adam Garcia’s British accent wearing off halfway through the episode, the fact that the British Prime Minister represents the planet rather than Hollywood’s preferred Presidential option. Poor Jackie gets left behind again, whilst the relief when the Doctor finally does wake up, it’s unparalleled.

The two crucial things we learn in this episode:

“No second chances. I’m that sort of a man.”

And:

“Don’t you think she looks tired?”

I can’t tell you the amount of times we’ve used that in real life, jokingly and otherwise.

As a self-contained story, it does okay, and with hindsight, it does affect some of the things that happen later. Really, the purpose is to cement the relationship between Rose and the Doctor. He’s changed, but he’s also the same, and crucially, she still wants to travel with him… no matter what.