With just a few days to go until the animated, restored and thoroughly rejuvenated Power of the Daleks is released, 50 years to the day since it was shown on BBC1 - probably after the football scores and accompanied by egg and chips and a pea-souper at the door. It's a wonderfully evocative thought - and offers a pleasingly circularity to the autistic instincts of Doctor Who fans.
There's something else that's interesting about time here. 2016 will be the sixth year when there's new Doctor Who on television, albeit only once and at the very end of the year this time around when Peter Capaldi will be joined by Pearl Mackie and Matt Lucas in time for another sherry-soaked romp (ugh).
This year we have an anniversary treat (sort of) in the shape of Power of the Daleks, a story whose reputation has comfortably eclipsed Evil of the Daleks (fingers crossed that one will come along later if sales of Power... are promising).
There are good reasons for choosing Patrick Troughton's first story. As the introduction of the Second Doctor, forming a companion piece with the newly-restored The Tenth Planet, it has a cache beyond most lost stories, especially following the welcome recovery of The Web Of Fear. And on its own anniversary there's a ready-made story of its release.
However there's more. Every ten years after Power of the Daleks' original broadcast - give or take a few days, weeks or months - there has been new Doctor Who. And tracking the changes over those decades is a fascinating way of tracking Doctor Who's varying fortunes, contemporary television styles and trends, and the development of what is now undeniably a pillar of television history.
While Power doesn't suggest a radical change of the template from the previous three years, the paradigm shift to episode four of The Deadly Assassin is startling. 11 million people watched as Tom Baker's Fourth Doctor overcame Goth and the wizened new Master.
It's a violent, surreal and often horrifying story - shot in colour, frequently on location and film. For the first time the Doctor travels without a recognised companion and Tom Baker - at the absolute height of his powers - along with Philip Hinchcliffe and Robert Holmes is turning Doctor Who into must-watch television. It's an era rightly recognised as probably the best in the series' 50-year history.
Fast-forward 20 years later and there's another scouse Doctor at the TARDIS controls. Paul McGann's Eighth Doctor fights yet another version of The Master (and American TV executives) in millennial San Francisco, following a seven-year hiatus. Perhaps the most obvious influence on the TV Movie is The X-Files, but the prevailing idiom is apparent in Buffy The Vampire Slayer too.
In all honesty it's a wretched piece of television and a scarcely-recognisable bit of Doctor Who. The idea of a resulting series is fairly grisly in retrospect. Don't believe me? Try, if you can, to read the Leekley Bible without weeping.
Another ten years later and Doctor Who is back on TV screens feeling as confident as it had 30 years before. The Runaway Bride holds little interest for me but there's no doubt The Tenth Doctor's Christmas romp (ugh) has a very strong sense of what it is doing. A scene where the TARDIS barrels down a motorway to rescue a bride (played by perhaps the most popular comedian of the day) being kidnapped on her wedding day by evil robot Santas is practically the perfect evocation for Russell T Davies' Doctor Who.
Perhaps the most intriguing update in this ten-year cycle though is The Trial Of A Timelord. It's also the first of these stories I ever saw, coming at a time when I had abandoned Doctor Who for daring to kill off my Doctor (the Fifth) and present me with probably the worst run of stories in Doctor Who's history.
I still devoured Doctor Who in Target form but Colin's abrasive Sixth Doctor and a dysfunctional production office had ensured television Doctor Who lost me for several years, bar a chance (and chilling) encounter with the first episode cliffhanger of Terror Of The Vervoids.
A recent rewatch of the entire boxset has confirmed that The Trial of a Timelord remains intriguing in Doctor Who history, albeit flawed - in different ways but to similar degrees - to the preceding season. Colin Baker has clearly mellowed his performance from the previous year and it's noticeable that the first time we see Peri and The Doctor they're conversing like normal people. Both leads have lovely moments together and the folly of the fractious relationship in Season 22 is immediately clear. There's also the single-most impressive special effect in the series' history as we see the Gallifreyan space station capturing the TARDIS.
Sadly it doesn't last. Robert Holmes' last complete story is every bit as dull as his first. The Mysterious Planet is limp, ponderous, confusing. It's immediately clear that Doctor Who hasn't made a glorious return. Later in the series we get an enjoyable potboiler in the shape of Pip and Jane Barker's Agatha Christie pastiche and more strong work from Colin, at last the Doctor we know and love from Big Finish, where he delivers easily the best performances of all the Doctors. But it's clear that this story is not the programme's resurrection.
It's only in Mindwarp in Trial of a Timelord where Doctor Who suggests that there's a viable, exciting vision for the show. This is unsurprising as it comes from the only person who could be described as an auteur working on the show at this time. Philip Martin's track record of playing with narrative and convention may not completely translate here, but Mindwarp's unreliable narrator, state-of-the-art effects and tonal shifts between high camp and brutality are, at least, novel.
Colin Baker's prickly Sixth Doctor feels more at home here and the character comes into his own. And the radical tone feel vitals in the prevailing political and economic situation at the time - a convincing example of science-fiction as satire. Mindwarp is thrilling, funny, weird - and shockingly powerful. Needless to say, Martin never wrote for Doctor Who again.
And then there's The Ultimate Foe (the aborted Time, Inc). The loss of this story is small beer in relation to Robert Holmes' premature death, but it does deny us his final vision for the programme he will be forever remembered for. And what a vision it offers. If modern Doctor Who is all about revelation, story arcs and narrative twists, this is where it all starts.
The Trial of a Timelord roughly mirrors the modern show's quarter-year run and its season-long story arc. It also builds to a stunning revelation the series has probably never - and could never better. The Doctor's arch foe, who has spent the previous 12 episodes demanding his life, turns out to be... himself. That this news is delivered by The Master, who has also turned up just in time for the climax of this epic story, accentuates the sense that what we're seeing is something very special. Just image the social networks lighting up at twist upon twist that The Ultimate Foe throws at he audience.
It never really turns out like that, as the story devolves into a confusing runaround. Quite what Holmes' vision was we can never know. Eric Saward's patch-up job at least attempts the kind of pay-off - the Doctor and the Valeyard tumbling the Matrix in mortal combat - the set-up demands but it's understandable than John Nathan-Turner was skittish about leaving the story unresolved, lest Jonathan Powell see an opportunity to close the door on his own bete noir for good.
In The Trial of a Timelord there's an unwitting echo of the template that would become familiar in the 2005 series onward. And it sets off one of the most fascinating narratives in the show's massive 53-year universe.
The story of the Valeyard - created by the Timelords as an amalgamation of the Doctor's darker instincts - is never really resolved but the phenomenon creates space for successive writers in audio stories and original novels to explore. The Seventh Doctor is haunted by the Valeyard and the space created by the Sixth Doctor's unresolved television adventures have created a whole sub-universe to explore this facet of the Doctor's consciousness.
Colin Baker's personal misfortune nevertheless creates one of the most bizarre and compelling strands of the expanding Whoniverse. It's something of a microcosm for the Trial of a Timelord which, although largely unsuccessful, has remained interesting in a way that superior stories arguably have not.
This may or may not excite you but it clearly stayed with Steven Moffat, who essentially re-ran the storyline in the excellent Day of the Doctor 27 years later. I believe there's something interesting to be said about almost all Doctor Who. Even when it fails it often does so brilliantly. Doctor Who fails on its own terms.
We're about to get one of the most superior stories in the show's history returned to us on its 50th anniversary. But we're also 40 years on from one of the show's finest hours, with its most recognisable Doctor. The TV movie is an odd landmark, but a landmark all the same; The Runaway Bride is modern Doctor Who perhaps at the apex of its mainstream popularity. Capaldi's Twelfth Doctor has been an undoubted triumph, with Steve Moffat on a victory lap: Doctor Who on Christmas Day is as much of a tradition in the modern age as the Queen's speech.
But let's not forget The Trial of a Timelord. Mark Gatiss once said that Reece Shearsmith had become obsessed with it. It's not hard to see why it holds a peculiar fascination. It's rare that such a mainstream programme is so odd, so ill-judged has been commissioned - the trial framework hobbles any attempts to make the show more dynamic, saps its pace and undermines its drama. Yet Trial of a Timelord flickers and sparkles with moments of brilliance and a conclusion that has attracted writers like moths to a flame ever since.
That the serial ends with a succession of real-life disasters has given it a meta quality. It's impossible to watch the last of the Sixth Doctor without associating it with Colin Baker's love/hate relationship with the show. Perhaps Colin is similarly ambivalent about his swansong.
In Robert Holmes' last episode we glimpse genius. The stunning nighttime location work; the Doctor at war with his future self; the return of The Master. And the knowledge, in retrospect, that the stakes were so high in fiction and in reality. It feels as if Doctor Who has stumbled across something it can do well, something important and daring. It doesn't last, in fact it's the calm before the storm, but alongside The Power of the Daleks it's right to look back on episode 13 of The Trial of a Timelord. We can reflect on what might have been, but we can cherish 20 stunning minutes of Doctor Who amid 14 weeks unlike any other.
3.7m people watched The Witch's Familiar - just the second episode of Season 9 of the rejuvenated Doctor Who, starring Peter Capaldi as the Twelfth Doctor. Not since Battlefield back in 1989 has Doctor Who ranked so lowly in live audience viewership.
However you look at it, this is a startling fall from Deep Breath's debut barely 12 months ago, which hauled in 6.8m 'live' viewers, and even the least-watched episode from last year, which was the underwhelming The Caretaker at 4.89m.
Without venturing into the yes-it-is-no-it-isn't nonsense of arguing over statistics, Doctor Who's audience figures have been remarkably stable over the last five years, hovering around 7-8m every week once the tricky assimilation of catch-up, on-demand and other sources are taken into account. Whether it's been scheduled at the standard 7pm-ish start time, earlier or later; against Ant & Dec, X-Factor or live sport; in Spring or Autumn; starring Eccleston, Tennant, Smith or Capaldi. The latter's debut season, Season 8, averaged out at around 7m - the lowest since the series returned in 2005.
The last two weeks suggest that even an average figure of 7m is no longer attainable. The final audience figure for The Magician's Apprentice seems to be around 6.5m - and past viewing figures suggest, unlike the classic Season 26, they are likely to decline across the 12-episode run. Yes, the figures for The Witch's Familiar - scheduled opposite England V Wales game in the Rugby World Cup - were out of the ordinary.
As telling as the overnights however are the consolidated figures from The Magician's Apprentice. That this block-busting series debut episode - featuring the return of Missy, Davros and Skaro - couldn't muster anywhere near 7m suggests that the 2005 paradigm (just like its Dalek equivalent) is dead and buried.
What can this mean? The later timeslot, over-familiarity with Moffatian scripts, less engagement with the TARDIS crew and, perhaps, fatigue with the show's massive profile over the last ten years seem to have caught up with it. Perhaps engaged youngsters will be inclined to view on catch-up, but maybe there's a risk that the later scheduling will not pick up young viewers who are unfamiliar with the show.
The potential threat to Doctor Who is its future as an ongoing television programme.
Unlike Battlefield - a story scheduled on the same day, at the same time, as the previous eight stories, with only three other channels realistically possible and without the attendant complications of time-shifting - there are many factors involved in figuring out what's happening with Doctor Who's viewing figures. Either way it seems beyond much discussion that the show is slowly but steadily shedding viewers.
In 1989 relatively weak viewing figures were given as the main reason for 'resting' Doctor Who, despite a consensus that the show was enjoying a quality not seen as constantly since the 70s. But Doctor Who is currently in no danger - as a brand. The potential threat to its future is as an ongoing television programme.
It's possible to extrapolate - via BBC America and Worldwide revenues, where Doctor Who is the best-rated and described as a 'top three' brand respectively - that Doctor Who is worth at least £75m annually (BBC America and Worldwide have reported annual revenues of $550m and $1.8bn as recently as 2012-13). That's a very wonky guesstimate but, given its extraordinary merchandising potential and increasingly global reach, it seems not an unreasonable one. It's also self-evident that it doesn't cost that much to make it every year. Given that the Beeb has already lost one-third of its top-three performers in Top Gear this year, it's unlikely to to be keen to write off another.
But there are people behind the scenes waiting for their turn to make a Doctor Who movie, eyeing up the potential of a franchise as big as Harry Potter. If money is the reason that Doctor Who won't be leaving the public eye any time soon it's also the reason why it might leave the small screen.
Central to all of this is the role of Steven Moffat, Doctor Who's show-runner for almost six years now. Moffat has written or co-written 40 full episodes of Doctor Who by now, with the latest of these set to go out at the end of Season 9. That makes Moffat comfortably the most prodigious writer in Doctor Who, as far as television is concerned. Add to this his myriad responsibilities as show-runner, which can only be guessed at, plus his responsibilities as show-runner and writer on Sherlock.
That this man, in his mid-50s, has the energy to continue in these responsibilities is extraordinary - Capaldi recently said that it's "absolutely vital that we have Steven working on it and having a vision on the whole thing" - but they also allow him a level of influence previously unseen in British television. When an attempted coup was launched in 2011 with news of a rebooted Doctor Who on the big-screen by Harry Potter director David Yates, Moffat's response was, by the terms of public discourse, remarkably brutal. Behind the initial announcement was Jane Tranter, key to the return of Doctor Who in 2005 and then the head of BBC Worldwide. It's not clear what the view within White City may have been, but Worldwide are clearly itching to make a Doctor Who movie.
Moffat's curt response at the time was to describe reports of the film as a 'weird fantasy' - later explaining that the notion of rebooting Doctor Who was 'nonsense', 'insane', 'intolerable' and 'a straightforward insult to the audience'. In the meantime there have been several forays into cinemas for Doctor Who - and the unprecedented (since 1963) repeat BBC1 showing on a Sunday afternoon. Both are interesting developments given the tension between TV and cinema - and the current ratings slide.
What's more, in a 2015 radio interview Russell T Davies declared that he'd be delighted to be asked to write a Doctor Who film. That Tennant and Billie Piper clearly remain the TARDIS crew most firmly embedded in the public's consciousness - and that both are still of an age to be considered sufficiently bankable in Hollywood - adds grist to the mill, no doubt to Moffat's dismay.
More recent comments have suggested more equanimity, with Moffat conceding that the show belongs to the BBC and it's very much up them. But leaked emails between BBC Worldwide and Sony suggest that bean-counters are very keen but the creatives are putting a block on a movie. This, quite clearly, means Steven Moffat.
Seen in this context, there is a power struggle over Doctor Who - an extraordinary position for the show to be in given how toxic the show was to the BBC in the 80s and 90s. But just as Russell T Davies was finally allowed his turn to make Doctor Who on television following repeated failures of the BBC and various US partners to make a film, could a combination of Worldwide and US studios be poised to launch their bid for a movie franchise in the context of dwindling ratings? Those leaked Sony emails also revealed that the BBC believed there'd be a film 'within eight years' and that the current TV production team were committed to including a film within that timeframe.
Currently there is no commitment to a whole series in 2016 and we know that one of the sticking blocks over a film is that it would take a good 24 months to write, shoot, market and distribute a film. That could mean no Doctor Who on the small screen for three years, by which time Peter Capaldi would be 60. Co-ordinating the way that the film industry works with the extremely fast-moving world of TV entertainment will be a challenging proposition for anyone.
At the same time an overworked Steven Moffat is surely nearing the end of his time with the series. It's two years since he admitted in a DWM interview that he was nearer the end - of his time as show runner - than the beginning. But if Moffat cannot block a Doctor Who movie then surely he'd want to write it? For the money, for the profile, for the bouquets and also because he'd want to make sure that any film was true to the show's established ethos and history. No reboot, no parallel continuity, no gun-wielding Doctor, pneumatic companion or rapping TARDIS.
If we assume that all of this is broadly correct, or not wholly incorrect, the dwindling viewing figures for Series 9 - and concomitant suggestion that Moff's writing is losing its appeal and Capaldi does not have the broad appeal of Tennant and Smith - might make the prospect of a Doctor Who movie more likely.