The following is based on official material about the episode, as released by the BBC, along with speculation about that material and about previous episodes of Doctor Who. It also contains information showrunner Steven Moffat has shared with us, plus one or two other snippets. That being the case, it could contain spoilers but it does not knowingly use any of the leaked information published recently in certain newspapers, which I deliberately avoided reading.
So. The Doctor Who 2013 Christmas special, then – what do we know so far...?
What’s it called?
First we had The Name of the Doctor, then we had The Day of the Doctor and this Christmas we find ourselves in… The Time of the Doctor…
A suitably portentous title to round off Matt Smith’s farewell trilogy and, more than ever perhaps, that word Time seems to be key here. In the first promo shot for the episode, a grave looking Doctor is pictured in front of a clock striking midnight.
Matt Smith's Time is up, we know that, and so is the Doctor's based on what Steven Moffat told us recently about regenerations – except he's obviously found a way to keep the Time Lord ticking, because Peter Capaldi's Time is coming.
It's about time...
When’s it on?
Ignore the clock in that first shot from the Doctor Who Christmas special – The Time of the Doctor is not midnight, but 7:30pm, on Christmas Day, Wednesday 25 December.
And as well as fighting Daleks and Cybermen, the Doctor will find himself up against Coronation Street, which runs across the same hour – 7:30-8:30pm – over on ITV.
Who’s in it?
The Doctor – Matt Smith
The Doctor – Peter Capaldi
Clara Oswald – Jenna Coleman
Orla Brady – Tash Lem
Aside from the three obvious names – one of whom may make only a brief appearance – we know that Orla Brady, of BBC1's Mistresses and US sci-fi show Fringe, will play the pivotal role of Tash Lem, a figure from the Doctor's past.
Further names here as we get them.
Which monsters are involved?
The initial synopsis tells us to expect “the massed forces of the universe’s deadliest species”, and the 11-second trailer pretty much backs that up, showing us glimpses of Cybermen, Daleks, Silents and Weeping Angels.
The Silents also appear, looming ominously (what else?), in the background of the first promo image, while the Doctor is holding the battle-scarred head of a Cyberman (which, intriguingly, has had makeshift repairs made to it).
As far as we can make out, the Daleks in the trailer look like “ordinary” models but Radio Times readers will note that the cover of the new issue features Matt Smith flanked by Mark Gatiss's "big buggers" – the New Paradigm/Teletubby/Renault Megane-style Daleks that the Doctor failed to deal with in Victory of the Daleks.
Oh, and that's a Sontaran ship spied over the Doctor's shoulder in the latest promo image. Does that mean another enemy to add to the mix – or a friendly (if potato-shaped) face in the form of Strax?
What’s going to happen?
“Orbiting a quiet backwater planet, the massed forces of the universe’s deadliest species gather, drawn to a mysterious message that echoes out to the stars… Rescuing Clara from a family Christmas dinner, the Time Lord and his best friend must learn what this enigmatic signal means for his own fate and that of the universe.”
The Doctor is returning to Trenzalore, the site of his tomb and the place where fat blue prophet Dorium Maldovar says “the fall of the Eleventh” will take place. We had always assumed that meant Matt Smith’s Doctor but with the recent arrival of John Hurt’s ninth incarnation potentially bumping subsequent Doctors up one, I suppose that's now open to debate.
Religious movement The Silence – headed up by, but not to be confused with, The Silents – believe, according to Maldovar, that “On the Fields of Trenzalore, at the fall of the Eleventh, when no living creature can speak falsely or fail to answer, a question will be asked – a question that must never ever be answered: ‘Doctor who?’”
At least part of that prophecy appears to have already been fulfilled the last time the Time Lord visited Trenzalore in The Name of the Doctor. But "Silence must fall when the question is asked" says Maldovar, and "Silence will fall" says the trailer for the Christmas special. Whether that means the Silence, the Doctor (or just that it all goes a bit quiet), remains to be seen...
Is the Doctor dying?
Following the introduction of John Hurt's new ninth Doctor – along with confirmation from Steven Moffat that tenth Doctor David Tennant did indeed use up a second batch of regeneration energy to heal himself – we now know that Matt Smith is the 13th and final of the generations Time Lords are usually allowed.
We also know that his Doctor will talk of "dying" in an emotional speech in the Christmas special.
"The 12 regenerations limit is a central part of Doctor Who mythology," Steven Moffat told us recently, "science fiction is all about rules, you can't just casually break them.
"So if the Doctor can never change again, what's Peter Capaldi doing in the Christmas special?"
A good question, and one that will only be answered In the Time of the Doctor...