Another of those John Sutherland-esque puzzles: in The Five Doctors the second Doctor realises Jamie and Zoe are phantoms because he knows that at his trial their minds were wiped of their adventures with him; while in The Two Doctors he’s able to steer the TARDIS and intervene at the request of the Time Lords. However, in the 1960s the second Doctor was famously unable to direct the TARDIS, was a desperate renegade from the Time Lords, and, when finally tracked down, was forced to regenerate by them soon after saying goodbye to Jamie and Zoe. Therefore, how can the 1980s stories be reconciled with the second Doctor’s 1960s’ adventures?

Since 1995 and The Discontinuity Guide, the preferred answer has been “Season 6(b)” – that after his trial the second Doctor was spirited away by the Celestial Intervention Agency and employed by them as a kind of time agent until they eventually decided to carry out the court’s sentence, change the Doctor’s appearance and exile him to Earth. Terrance Dicks was so taken with the idea that he wrote a BBC Book, World Game, to expand on it. It is an elegant theory, which has been expanded to explain the second Doctor’s aged appearance in the 1980s’ episodes and how Jamie knows about the Time Lords in The Two Doctors despite having heard about them for the first time in the final second Doctor story The War Games.

However, while the second Doctor’s continuity errors are the most egregious (and baffling, given Terrance Dicks wrote both The War Games and the contradictory Five Doctors), it’s hardly as if the other past Doctors have perfectly adhered to continuity in their own return appearances. For example, in both anniversary stories, the first Doctor seems to spend all his time pottering round country gardens like a National Trust membership card holder just like he never did in the 1960s. And, as Tat Wood and Lawrence Miles observe, nothing can explain the state of the third Doctor’s hair in The Five Doctors.

Wood goes to great lengths to challenge the 6(b) consensus in About Time: Volume 6, arguing that it creates more problems than it solves, and proposing instead that the second Doctor has been summoned by Time Lords from his own future (and the sixth Doctor’s present) to intervene on Space Station Camera; that there are lengthy gaps between the second Doctor’s broadcast 1960s’ stories when this could happen, and that the second Doctor’s foreknowledge in The Five Doctors comes from him remembering his briefing from the future Time Lords in The Two Doctors. Phew.

Wood’s hoop-jumping is less compelling, and less elegant, than The Discontinuity Guide’s, however he does make the valid observation that it undermines the emotional climax of The War Games to argue that the second Doctor just saunters off afterwards for decades more adventures. And it’s difficult to disagree that the Time Lords as presented in The Two Doctors are clearly the corrupted, post-1976, Robert Holmes versions and not the pre-1976 Olympians. Why, you wonder, would they not – as usual – get the third or fourth Doctors to do this job?

Of course, whatever explanation you prefer is clutching at straws to explain away the fact that multi-Doctor stories are inherently problematic but intriguing examples of the developing mythology of the show. The template and most successful remains The Three Doctors – written when the idea of physically regenerating the body hadn’t yet been established, with the change presented instead as a metaphysical process. In The Three Doctors, it isn’t the second and first Doctors physically being brought back as such, but other aspects of the third Doctor’s existence in a kind of psychic shared persona – Troughton’s id, Hartnell’s ego and Pertwee’s super-ego – which have to come together in the face of the threat posed by Omega’s vast willpower. The original storyline, which had the earlier Doctors sacrifice themselves to save the third, made this explicit, and there’s still a hint of it in the way the two Doctors explain themselves to Jo. In The Five Doctors there is more of a sense of five different personalities thrown together for an adventure – but this isn’t just a timey-wimey team-up: there is still a semi-mystical aspect, with the suggestion that the old Doctors are being somehow wrenched out of the fifth Doctor’s very being.

And this is the nub of it. “A man is the sum of his memories… A Time Lord even more so,” says the fifth Doctor. As his past lives are drawn to the Death Zone, the fifth Doctor fades away. He’s being picked apart, piece by piece – “diminished” as he says. The old Doctors aren’t only being summoned from the past, or from the Matrix. They are in some sense being drawn out of the Doctor himself, “detaching themselves like melting icebergs”. The Castellan’s exclamation that, “The Doctor no longer exists – in any of his regenerations!” makes it sound more like the eleventh Doctor’s fate in The Big Bang – the past Doctors haven’t just been snatched from moments in history, but ret-conned out of existence entirely. In a story that’s all about the remembered past, this makes absolute sense (as well as neatly resolving any continuity issues with Shada, if the scene is just the Doctor’s remembrance of that adventure). Castrovalva features the fifth Doctor briefly slipping into the personalities of his previous selves, while in the New Adventure Timewyrm: Revelation, Paul Cornell has all of the previous Doctors living on inside the current incarnation’s head. The first Doctor has a garden just like in The Three Doctors, and the fourth is a ferryman in imagery clearly lifted from the Shada clip. And as we now know, “anything that can be remembered can be brought back”. Cornell’s implication is obviously that in their return appearances, the past Doctors are extrapolated from the current incarnation. And, as he so often does, Cornell gets his inspiration from Terrance Dicks. In this argument, the second Doctor remembers his own regeneration because the fifth Doctor remembers it, and regardless of what face he wears, he’s the same man.

However, there is another argument: that the past Doctors continue to have some kind of existence after their respective regenerations. This is based on what we know of the fate of dead Time Lords – their personas continue to exist inside the Matrix, a vast repository of brain patterns taken at the moment of death. We might extend this to mean the Matrix stores the brain patterns of every incarnation of every Time Lord taken at the moment of death: a kind of “death mask” of every persona, or, less ghoulishly, a kind of virtual reality retirement home where they continue to exist in their own constructed worlds. We also know from The Trial of a Time Lord that it is possible to physically remove something from the Matrix reality – not just as data, but actually as an object. How much more difficult would it be, then, for a “dead” incarnation of a Time Lord to be summoned back?

If that’s possible (and the 21st Century resurrections of the Master and Rassilon suggest it is), then perhaps in The Three Doctors the vast power drain required to conjure up the first and second Doctors, and the Time Lords’ reluctance to do so, was because they were giving physical form back to what essentially is the past Doctors’ ghosts – a nice reflection (if entirely counterfactual) of Omega’s own dilemma. The second Doctor certainly fades into existence in our world, rather than arriving in a remote-controlled TARDIS, while the first is stuck as an image on a monitor, much like the Master communicating from the Matrix screen in The Trial of a Time Lord. In that case, the second Doctor really is a second Doctor – like the meta-crisis tenth Doctor he has an existence entirely independent  from the original.

And once the second Doctor does regain physical form, it’s not necessarily that easy to contain him back inside the Matrix – hence him impishly breaking the laws of time to visit the Brigadier in The Five Doctors (which clearly occurs after The Three Doctors given he remembers his own “pretty unpromising” replacement). This would also explain how the second Doctor could have memories of his own regeneration in The Five Doctors – he really is “dead” at this point. And when he pops up again in The Two Doctors, it’s at the behest of the 1980s’ Time Lords (explaining how he can have a Stattenheim remote control when the sixth Doctor knows he never did): the CIA making the most of a bad situation to make some use of this resurrected and out-of-time Doctor to do their dirty work, rather than relying on the unstable sixth.

And if you wanted to stretch the point to say the other Doctors were also plucked from the Matrix – the first Doctor’s resurrection goes a bit wrong in The Three Doctors, hence his altered appearance in The Five Doctors. While the third and fourth Doctors are clearly living in their own personal heavens at the start of that story, the third speeding around country lanes in Bessie, and the fourth spending a sunny afternoon bantering with Romana.

But essentially, this is a problem of the second Doctor’s impossible memories. None of the other past Doctors in The Five Doctors demonstrates any anachronistic foreknowledge. How does the second Doctor remember his own regeneration? Because he has literally and metaphorically been brought back from the dead: an entirely apt fate for this most anarchic and irrepressible incarnation.