Duoh! I forgot that David Tennant’s incarnation regenerated TWICE! In the two-part climax to Series 4 (The Stolen Earth / Journey’s End), the Doctor begins to regenerate after being shot by a Dalek. Having healed the injury however, he channels the remaining regeneration energy into his old severed hand, thus enabling him to regenerate without the customary change in appearance and personality. I guess I never thought that counted, but having achieved the essential purpose of regeneration, I guess it must have.
One wonders if the Doctor himself realises this however. In Let’s Kill Hitler, he realises he is unable to regenerate because of the particular qualities of the toxin with which River has poisoned him, but he seemed to have been hoping it was an option. He threatened the Cyber-Planner with using regeneration as a means to burn it out of his mind and body in Nightmare in Silver, but that could have been a bluff. The aborted regeneration (the Doctor having been shot by a space-suited River) in Series 6 turned out to be “special effects” generated by a Teselecta, so that was a red herring.
But if – now that the War Doctor has been inserted and Tennant’s Doctor consumed an extra life – Matt Smith is the 13th Doctor, then all of his permitted regenerations have been consumed. I always thought it unlikely that nature would have given Time Lords such a specific fixed number of regenerations; indeed, the fact that the Time Lord authorities are known to be able to grant new regeneration cycles suggests that the limit is artificially imposed, perhaps as part of a wider moral or ethical philosophy (Rassilon himself having been, in some accounts, corrupted by his desire for immortality). So I was counting on Series 8 being a quest by the new Doctor (who I assumed would be the 13th) for Gallifrey and his lost people, bringing with it the reward of a new regeneration cycle.
But there is the fact that River Song sacrificed all of her remaining regenerations to cure the Doctor of Judas Tree poisoning in Let’s Kill Hitler. She had regenerated twice and had the energy of ten more in her system. How many of them were needed to “regenerate” the Doctor – again without changing his appearance – is unknown. He seemed to have a bit of surplus energy floating around to heal River’s broken wrist in The Angels Take Manhattan, a feat I’ve never known him to perform before.
So what happens? Has he got multiple regenerations left, River having given him far more energy than was really necessary to resuscitate him? Has he got just enough for one more, after which Peter Capaldi’s new 14th Doctor had better watch out? Has the presumably artificial limit been somehow “shorted out” (due to the influx of River’s energy, or perhaps due to the absence of the Time Lords’ enforcement?)? Or perhaps something very special will happen within the Christmas episode itself which will explain all?
I can’t wait to find out. With parents-in-law who hate Doctor Who being around on Christmas Day however, I suspect The Lad and I won’t be seeing it to review it until Boxing Day (assuming BBC repeat it). Sigh…
[FAKE SPOILER: Here’s my guess, for what it’s worth. Trenzalore is Gallifrey, and the clock tower is a great big Chameleon Arch effectively hiding the populace by disguising them as humans. The Doctor’s enemies have found out and are trying to destroy it… Oh well, it’s a guess anyway, Who knows?]