The Five Doctors

Chapter The 148th, where Tom Baker is missing but probably still in the pub.

Plot:

Every Doctor to date, and whichever companions were available, work-permitting, are gathered up by a Time Scoop operated by a mysterious person unknown on Gallifrey. The fourth Doctor (scarf, bohemian, curly hair) and Romana are caught in the time vortex, but everyone else is brought, along with Cybermen and a Dalek and some other baddies, to the death zone, an arena used for gladiatorial-style games in Gallifrey's less enlightened past. The use of the scoop causes an energy drain, so the high council of Time Lords send for the Doctor; but, finding that his time traces converge in the zone, they send the Master in to save him. The fifth Doctor (cricket, celery, blonde hair) escapes the zone and investigates who the traitor on Gallifrey might be, and finds out that it is President Borusa. The three remaining Doctors (grumpy one, flautist, dandy) separately battle against all the obstacles, and converge on the Dark Tower at the centre of the zone, where Time Lord legend Rassilon is rumoured to still be alive and handing out immortality as a prize for passing the tests. Borusa arrives with the fifth Doctor, and - against the protestations of his other selves - the first Doctor tells Rassilon to give Borusa the immortality he seeks. But it's a trap, and Borusa lives forever turned into a statue. The Time Lords want the Doctor to take over as president but he instead chooses to go on the run from his own people, in a rackety old TARDIS; that's how it all started, don't you know.

Context:

Accompanied by all the family (Better Half and three children - boys of 13 and 10, girl of 7), I watched this one Sunday evening, from the DVD. We watched the original version as transmitted in November 1983, Doctor Who's 20th anniversary. I kept the title a secret before I pressed play, and was greeted by a chorus of jeers that we were watching "an old black-and-white one", this being in reaction to the William Hartnell clip used as a pre-credits sequence. I'd love to say that the jeers turned to happy astonishment as soon as the 1980s Peter Davison titles sequence kicked in, but they were in a rowdy and mischievous mood throughout.

First time round:

This was a big, big deal at the time - an absolute event - and was trailed long before it aired in various ways. I must have known it was coming from Doctor Who Magazine, I suppose, and I remember that was months and months before it aired. It's certainly the first and so far only Doctor Who story where I saw the sets before I saw the programme. This was at the Longleat Twentieth Anniversary celebration, Classic Who's equivalent of Woodstock. I was there with my whole family, and saw - if I remember rightly - the High Council's meeting room, the UNIT HQ interior, and Borusa's secret control room on display in a marquee. I remember mentally creating my own stories as I walked round the exhibit based on this furniture alone (none were even close to being on the money, by the by).  Next, probably only a few days before transmission, I remember seeing a copy of the tie-in novelisation in WHSmiths (it was mistakenly available in some shops before the TV story had aired, which had never happened before and probably never happened after). I remember lovingly caressing the foil embossed cover, but I did not sneak a peek at the contents. Looking back, I can't believe I was so restrained and am really proud of my young self.

Next comes the bit where I'm less than proud of myself, alas. On the evening of Friday 25th November 1983, the plan was that I would not watch Doctor Who. My sister had a big role in a local am-dram production, and the whole family was going to be in the audience to support her. I was not happy about this, as I did not want to miss the biggest Doctor Who story ever. Friends of the family had promised to tape the show on their new-fangled Betamax top-loader video recorder, and we were visiting them the next day. But I didn't want to wait a whole day to see it, so - amidst shouting and recriminations from all around me - I feigned illness and refused to budge when everyone else left. I watched on my ownsome, sitting through a lot of tedious preamble from Terry Wogan, as Doctor Who was shown as part of Children in Need. Looking back, I feel bad, but at the time I was perfectly happy with my decision - I estimated that The Five Doctors must be considerably better than whatever lame old play my sis was in. I apologise for the crassness of young me. Watching it on Friday did not then stop me from wholeheartedly embracing the viewing on Saturday too. The chance to see something I'd watched the previous night again was something akin to the finest magic. If it hadn't been early 1980s UK, with only one TV per household on average, and certainly only one VCR, I might have asked to watch it all again for a third time; but, the adults wanted to generally be dull and talk or whatever in the living room, so my sister (who was still talking to me, just about) and I retreated to the kid's bedroom - his name was Michael, if memory serves - and talked about our favourite bits. 

I've seen this story a lot in different forms. I watched the repeat the following Summer, which split the story into four twenty-five minute chunks with the worst cliffhangers ever. I bought the VHS when it came out in the early 1990s. Then, in late 1995, a special edition version of The Five Doctors - with a small amount of additional material, improved sound and new effects - was made for release on that magic home format: video tape. By this time, I was very familiar with the technology. It came in a set with preceding story The King's Demons, plus two postcards of each story's cover art (as they had been giving away with all the releases that year), and an album to collect up said postcards, which was smart, and which I still have somewhere. This was special as it is one of one two Doctor Who videos I ever got as a Christmas present. In general, I always snapped them up as they were released, never leaving anyone the opportunity to get them as a gift. I can't remember what happened that year to make me hold off, but it was very nice to unwrap and watch on Christmas day. As I was watching the scene of the Raston warrior robot battling with Cybermen soundtracked in gorgeous beefy stereo, my sister wandered in and listened to the Cyber voices giving it their best take at anguish and devastation, and said "Blobby blobby blobby" then walked away. Fair enough, I suppose. 

Reaction:

Robert Holmes, one of the best regarded of twentieth century Doctor who writers, tried to plot a version of The Five Doctors and couldn't manage it: all the disparate elements, all the many leading men to cater for, all the chops and changes of actors' availability - it was too much. He stepped aside, and Terrance Dicks picked up the baton. They are both fine writers, and there was nobody else around then (and few have come along since) who knew more about writing Doctor Who than the two of them. So, why did Uncle Terrance succeed where Holmes failed? My guess is that Holmes was overthinking it. One thing every fan knows from Holmes's aborted storyline attempt is that at the end the first Doctor (played here by Richard Hurndall, standing in as original actor William Hartnell had passed away) is revealed to be an Auton, explaining why he doesn't look quite right. Dicks just ignores the re-casting and gets on with a straight-ahead action story. Dicks's ability to produce such a simple and effective narrative, given the egregious length of the shopping list of elements he had to include, should not be overlooked: what he overcame had defeated Robert Bloody Holmes, for goodness sake! As such, The Five Doctors is bulletproof when it comes to critiques. It was built to showcase twenty years of Doctor Who, and that it does - anything more than that is a bonus.

So, it's pointless to criticise the structure for being basic and linear: that's a necessity, but also a strength. There's an intro to each Doctor, as they are zapped out of existence by a black triangle. Then there's a bit of each walking around the death zone, before having a couple of exterior set pieces each. Then, they enter the tower, each coincidentally with their own entrance. Then an interior set piece each, then all together for the confrontation with the main villain at the end. Then goodbyes and off they go. There's a subplot about the conspiracy on Gallifrey, but that's as complex as it gets, and even that's only added to give one Doctor something to do, who otherwise would be stuck in the TARDIS (a fate that, as good as he is, Dicks can't help but deliver to two of the many companions involved). Of course it is structured like this: who has time to do fiddly intriguing subplots and reversals when you have to give sufficient action to four leading men (if Tom Baker had agreed to take part, my guess is Richard Hurndall would have stayed in the TARDIS with Susan and Turlough). This is probably why no reunion story of this scale has ever been attempted in Doctor Who since (with the exceptions of two skits of varying degrees of success - more on those below).

What can I say about any of those scenes that hasn't been said a thousand times before (and that goes for positives and negatives)? The use of footage from the unfinished, and at that point widely unseen, Shada to give Tom Baker's Doctor something of a presence in the proceedings is inspired, and the scene of the Doctor and Romana punting on the Cam contains some of Douglas Adams most charming and witty dialogue: "Oh I do love the autumn, all the leaves, colours" is such an unassuming punchline, and delivered with such panache by Lalla Ward, it makes one glad this footage got a BBC1 airing. Until the Special edition in 1995 "fixed" things, it had never occurred to me as odd that the picture used to represent the two Time Lords stuck in the vortex didn't match what they'd been wearing in the punt. It also never bothered me that the Doctor is returned to his timestream stuck halfway under a wire fence - it just seemed like a bit of a laugh. 
  
The scenes of the Raston warrior robot - the one original element included here - slaughtering a platoon of Cybermen is magnificent. One of the Cybers vomits - it's amazing! It's very satisfying for the obsessive statto nerds like me that Jon Pertwee finally got to encounter the Cybermen (which he never did during his original tenure). Troughton gets all the best lines, which is the sensible choice as he is the best at delivering them; partnering him with Nicholas Courtney as the Brigadier is successful too - they make a great double act. Hurndall is enjoying getting to be a hero (just for one day), and holds his own. The scene with him, Susan and the Dalek is nice, and it's great to see the shell exploded and the grisly, squiddly Kaled mutant inside for the first time in the series (that was an effect that they demonstrated at the Longleat celebration too, now I think of it).There's a cameo from K9, and another from Jamie and Zoe, and Liz Shaw screaming "Stop Hiiiiiiiiiiiiiiiiiim!" What more could you want?

One bit that most fascinates me is the chequered floor sequence featuring the Master, Cybermen, and the first Doctor and Tegan (Dicks's drafts are showing here - why on Earth would those two be paired unless it was a remnant of a version where Tom Baker was the one investigating the conspiracy on Gallifrey, and Davison was allowed to adventure in the zone with his longest-running companion?!). The director Peter Moffat was well known for bringing productions in on budget in as unfussy a manner as possible, to the point where his work can look terribly pedestrian. That isn't so much of a problem here, likely helped by a more generous budget than usual, and a lot of his work looks excellent - particularly the location footage in the Welsh hills, and the beautifully lit sequence with Troughton attacked in a cave by a Yeti. He couldn't make much visual excitement out of a tiled floor, though, but who could? It's a floor. What's annoying though is that Moffat doesn't seem to have thought it necessary to help the actors to work out what is the logic of this floor trigger puzzle, and move accordingly to sell it to the watching audience.

Anthony Ainley's Master walks inconsistently over it multiple times, with differing levels of care about exactly where he's treading.  On at least one occasion, his foot falls at a point where four different squares intersect. They paper over this by adding a line on how the safe path changes every time, but it's hardly satisfactory. Every time I've watched this - and that is more times than is healthy, believe me - I've scoured for any discernible rules to how the chessboard of death operates, and there are none. The scene still, though, intrigues me more and more - it just gives and won't stop giving. The Master tells the Doctor it's as "easy as pi" and somehow the Doctor hears this homophonic clue, even though it's far from obvious. Tegan is chided about her grasp of mathematics and says, haltingly "the ratio of the circumference of a circle to its diameter is represented by the Greek letter pi, right?" which is a 1980s companion language translation of the human English which would run something like "pi is that thing to do with circles, right?". But then, Tegan, on being presented with a keypad to open a door earlier, exclaims with astonished joy "An entry coder!" which is not an actual phrase that's ever been used by anyone ever. I was an entry-level coder once upon a long time ago in my day job, but it's not the same thing. Why aren't 1980s companions allowed to speak human? I suspect script editor Eric Saward of being behind this guff, as Terrance Dicks can usually craft rounded human characters who speak naturally.

Anyway, back to the killer floor covering, the laser lino: the Doctor muses on the application of pi to work out the safe route, pauses for a moment, then walks across successfully. But how? What has pi got to do with it? Is it each digit of pi in turn refers to the safe column to walk down? Or the unsafe one? How can the Doctor possibly work out the safe route just from that? Also, how did the Master know in the first place? He gets to that part of the tower after the Doctor and Tegan, and is never seen experimenting. How did he work it out? Also, once the Master has tricked the Cybermen into getting themselves killed crossing the floor, why can't the Doctor and Tegan just step on them to get to the other side? As I said, I may have watched this story more times than is healthy...

Connectivity: 

It's not very hard to link The Five Doctors to any other story as it contains such a broad coverage of elements from throughout Doctor Who history. Like The Android Invasion, it features appearances by Tom Baker as the Doctor and Elizabeth Sladen as Sarah Jane Smith, members of UNIT, blank faced robotic killers with their armaments built in, and creatures created by Terry Nation. In both stories, Sarah Jane is rescued from a pathetically un-steep cliff edge.

Deeper Thoughts:

First as tragedy, second as farce, third as farce again (but better). In the 30+ years since The Five Doctors, the series proper has never again tried to bring together such a crazy big set of Doctors and companions as the 20th anniversary story managed. It's done two Doctors working together with returning companions (The Two Doctors) and without (Twice Upon a Time), and two Doctors plus a new Doctor, and a brief cameo scene for all the Doctors using clips (The Day of the Doctor). It's brought back loads of old enemies but no old Doctors a few times (The Pandorica Opens, The Time of the Doctor), and that's about it. Someone must have worked out that it's damn near impossible to pull off a passable story again unless one keeps things more restricted, even if you have the talent of Terrance Dicks to write it. Lightning cannot strike twice. If one wants evidence of this, one only has to look at the time they did try such a feat again outside of the series proper: Dimensions in Time.

For the 30th anniversary in 1993, Doctor Who had been off air for a while, but was doing healthy business on sell-through VHS. There had been an idea to create a one-off feature length story specifically to be sold on tape, called The Dark Dimension. They would have worked out the 'too many Doctors for one plot' problem by giving the lion's share of the action to Tom Baker, and had the others pop-up for cameos here and there. The other Doctors, perhaps understandably, did not like this idea, and anyway the whole thing fell through. A consolation prize was that a short skit was going to be shot and shown - like The Five Doctors - as part of Children in Need. It was only about 15 minutes long, and split into two episodes, with a phone vote in between (nothing says early to mid 1990s like a pointless phone vote) to decide whether Mandy or Big Ron would appear in part 2. For you see, Dimensions in Time was a Doctor Who / Eastenders cross-over. Oh yes! It was rubbish of course, and watching it in my third year at university, old enough to know better, I clenched in embarrassment at Noel Edmonds taking the piss when introducing it.

The piece was shot in a 3D format that required objects to be placed unnecessarily in the foreground, and for the camera to keep circling all the time. As such, it is not recommended if you have a hangover. Tom Baker has his hair cut disappointingly short, and doesn't interact with anyone else, just appearing on his own in a prologue. Louise Jameson as Leela is dressed as Pocahontas for some reason, many companions don't look anything like they did when they were first in the show. There are no Daleks, so presumably Terry Nation had got in a strop and taken his ball away. Most of the interaction with the Eastenders characters is woeful. Frank and the Mitchell brothers handle it okay. And there's a great moment when Mike Yates arrives in Bessie, and he and the Pertwee Doctor drive off, meeting the Brigadier who arrives by helicopter. Then Pertwee turns into Colin Baker (did I mention that the Doctor and companions turn into one another rather than all appearing together? Oh yes!). This gives good fan service, just as putting Jon Pertwee with Cybermen in The Five Doctors did, as Colin and the Brig never got a story together on TV during his tenure. Kate o' Mara reprising her role as the Rani is great despite her over-ripe dialogue, and a young Sam West gets to act as her companion, and he comes out the other side with his dignity more or less intact. All the many villains are played by fans wearing old costumes, but en masse they acquire a sort of tatty majesty. 

The one thing that's missing is a joke, any joke. It is curiously humour-free for a skit, but this is not unusual in my experience of Children in Need or Comic Relief segments such as this. For a funny Doctor Who short one would have had to wait another 20 years for the marvellous Five-ish Doctors Reboot that was shown on the night of Doctor Who's 50th anniversary, which - in its own way - managed to reunite multiple Doctors and still have a sensible plot through-line. Anyway, Dimensions in Time was the only scrap of new Doctor Who shown on BBC1 between the end of Sylvester McCoy's run in 1989 and Paul McGann's one night stand in 1996, so it has a misplaced home in the affections of fans of a certain age (mine!). Because of the conditions of its making, with the performers working for charity, it can never be released on any home format or shown on TV again, but it can be found on the internet, if you've never seen it. Brace yourself! 

In Summary:

Five times the fun, just don't overthink it.

The Android Invasion

Chapter The 147th, where Tom Baker visits a pub several times (art imitating life?).

Plot:

The Doctor and Sarah arrive at what appears to be the village of Devesham, near a space centre where UNIT are currently based helping in the recovery of long missing astronaut Guy Crayford, who's returning from deep space (at least I'm assuming that's why UNIT are there - is it ever properly explained?). But the village is near deserted, and the people they do see are acting very strangely, and there's various hints that all is not right (all the coins they find are minted in the same year, a calendar only has one date over and over). The TARDIS team get split up after a attack by androids with motorcycle helmet heads and guns in their fingertips. The Doctor finds that Crayford is present in the space centre working with an alien race called Kraals who are creating androids copies of humans, including Harry and Sergeant Benton. Sarah makes her way back to the TARDIS, but sees the unmanned ship dematerialise and leave without her. Despite encountering android copies of each other, the real Doctor and Sarah are eventually reunited and realise that they are not on Earth, but are on the Kraal's planet: the village and space centre have been copied too, to act as a training ground for the androids.

Crayford, who has been brainwashed by Styggron, leader of the Kraals, is going to return to Earth in his spacecraft as a diversion, and the android copies will be shot to Earth in pods to aid the take over. The Kraals also plan to use a virus to wipe out all life on Earth (this doesn't make sense 100% but it's contractual that Terry Nation scripts must include a virus that wipes out all life). The Doctor and Sarah hitch a ride with the invasion fleet, and are shot towards Earth. Using the android version of himself to bamboozle his enemies, the Doctor stops the invasion. Crayford gets killed and Styggron falls foul of his own virus. The Doctor doesn't say a proper goodbye to Harry or Benton whom he'll never see again, and he and Sarah go off adventuring in the TARDIS once more.

Context:

This is a first for the blog I think. Started off watching part 1 (from the DVD) with all the children (boys of 13 and 10, girl of 7), but the Better Half entered towards the end of the episode and was intrigued, believing she'd never seen this particular story before. So, we had to repeat the experience a few days later, watching the first episode again, but amazingly, all the children re-joined us second-time round, and with just as much enthusiasm as first time. Thereafter, the family watched the remaining episodes on occasional evenings over the course of a week approximately. I made an effort to increase the mystery by not telling the kids anything about the story, and blocking the screen when the title came up at the start of the first episode. But on seeing the very first moments of action as the twitchy UNIT soldier walks straight toward camera, the youngest said "That's not a real person", and the middle child said "Yes, it's a robot". So, perhaps a longstanding criticism of this story - that its prosaic title gives too much away - is unfair, as it's clear the story is intending its audience to be clued in from the off. Everyone very much enjoyed this story, including me, which I have to say was a surprise as its reputation is of being under par - more on that in a moment. 

First time round:

I first remember seeing the novelisation in my primary school's library when I was a kid, so probably read it at one point in the early 1980s, though I remember nothing more than the cover: it was a good drawing, and the mysterious figures holding the Doctor wearing motorcycle helmets would likely have intrigued. The depiction of lead Kraal Styggron was rather better - and certainly greener - than it was on the telly box too. The first time I got to see the episodes would have been in March 1995 when they were released on VHS. This was one of the first pair of new releases that year (the other coming out at the same time was Carnival of Monsters), and both were the first to come with a free postcard of the cover art, which was a gimmick that they ran with for the next year. As per my standard behaviour pattern at that time, I would have purchased it in Volume One, an independent book and video store in Worthing, on its day of release.

Reaction:

This story comes from a period that to many fans is the golden age of Doctor Who: Tom Baker as the bescarfed Doctor - cheeky but commanding, and now fully settled in after his first year - travelling the universe with Sarah Jane Smith, righting wrongs. When they both step out in part one of his story, they do look amazing on screen together, and the chemistry between them makes them one of the most iconic of teams to ever helm the TARDIS. This particular story, though, is not necessarily as well regarded. The stories either side of The Android Invasion as originally broadcast, Pyramids of Mars and The Brain of Morbius, were the second and third Doctor Who VHS releases ever, coming out in the mid 1980s, a period when BBC Video had decided that stories where Tom Baker righted wrongs, usually accompanied by Elisabeth Sladen as Sarah Jane, were what the public wanted. Why is it that The Android Invasion never comes near the top of any polls, is never included in the list of classics from this era, and did not see the light of day on tape until 10 years later?

One theory is that the story's undermined by any mystery regarding the antagonist being blown by the title. Writer Terry Nation has form in this regard, with all his 1970s stories featuring his creations, Skaro's finest, named in the giveaway "Something of the Daleks" format. But here, the mystery of the story is clearly not intended to be that androids feature, which is confirmed early on (and is obvious from the first moments if my children's reactions - see above - are anything to go by). The real mystery is about the village, and the odd clues found there; the big reveal is that the TARDIS has landed on an alien planet and not the sleepy English countryside at all. And that mystery and that reveal are a perfect fit for the audience of Doctor Who, particularly the younger ones, to enjoy. The scenes of the eerie deserted streets and buildings of Devesham are great, and the moments of all the impassive robotic villagers are pretty creepy. The similarly blank-faced motorcycle helmet androids are visually arresting too, and the finger guns are a nice touch, easy for kids to emulate in the playground. Tom Baker gets to gently tease the concept - "Is that finger loaded?" - without undermining it. The Kraals look good, though there's only two of them. Nation unshackled from having to deliver yet another Dalek story has produced some good work. Overall, the story's got a lot going for it.

Perhaps the story is overlooked because it is something of a throwback. The presence of UNIT regulars, and the direction of Barry Letts (producer of the stories of Tom Baker's predecessor as the Doctor, Jon Pertwee) means it is quite backward looking at a point where the show was striding out into new territory. In the later years of Pertwee's time, with the narrative reason given that the Doctor's freedom to travel in time and space had been returned to him, the Earthbound stories where the Doctor worked with UNIT were being gradually reduced in number, and fewer and fewer of the previous ensemble cast of regulars were appearing in them. Letts' successor as producer Philip Hinchcliffe seemed happy not to make major changes to the format, but it seems clear that the stories that travelled the universe were the priority and nobody's heart was fully in making more old school tales. This is the second UNIT story of Hinchcliffe's producer-ship and arguably the last (the later story The Seeds of Doom is nominally a UNIT one, but contains no returning regular cast, and the soldiers in it, who only arrive towards the end of the story, could be any fighting force).

It's such a shame that the Brigadier gets no proper send-off, and instead is represented by an empty office with his name on it occupied by a hastily cut-and-pasted in replacement. Actor Nicholas Courtney wasn't available for The Android Invasion, and instead the crudely similar but nuance-free character of Colonel Faraday appears (who coincidentally seems to be performed almost exactly like Peter Glaze's take-off of the Brig in the Crackerjack Who pastiche skit "Hallo my Dalek" which aired a few months before The Android Invasion was broadcast). Being available and in the show doesn't protect a character from having a rubbish send-off either. Ian Marter as Harry Sullivan and John Levene as Sergeant Benton both appear, but don't have much to do, certainly no big heroics, in their final outings, and disappear by the end quite abruptly. Of course, it was likely that nobody necessarily thought they were going to be their final outings at the time. This isn't that big a deal, and certainly is no explanation for why this serial is undervalued, it's just a shame, that's all. The best inclusion from the previous era is Letts himself, who manages some impressive material here, particularly the generous amount of film used, but also some subtle use of green-screen to make things look more expensive and expansive than the budget allowed.

One final stick that's often used to beat The Android Invasion is the ridiculousness of the Crayford eyepatch subplot. Milton Johns, in one of his many Doctor Who appearances, plays Crayford as earnestly grateful for the rebuilding of his broken body after his rescue by the Kraals from his spacecraft crash. The only part of him that could not be reconstructed is his eye, covered with an eyepatch until near the end. There is, though, nothing wrong with Crayford. People think it stretches credibility that he hasn't checked at any point to see if his eye still works - but the script clearly states that he's been brainwashed. That's not to say there isn't silliness in the plot, but for some reason the focus is on the eyepatch when in fact it's everything else that doesn't make sense. Styggron's plan is to distract Earth with the return of a missing astronaut, and fire androids to Earth in pods to take over in key positions. But his plan is also to destroy all humans with a virus. He really doesn't need both plans, and they conflict with one another. If the pods containing androids will just be mistaken for meteorites, then why does he need the misdirection of Crayford's return? He could just fire the pods to Earth without putting monitoring on alert for a returning spacecraft - which could, after all, endanger the plan - freeing him up to be able to kill the weak link that is Crayford. Or, assuming he needs a ship to get close enough to launch the pods, then why not just make an android copy of Crayford to pilot the ship and speak to mission control? It would be more efficient than brainwashing, and the technology clearly exists to make it happen. Then, if he could use all his supposed Kraal genius to work out a way to just shoot the virus to Earth in the pods, he could cut out the need for any other androids, and all that faff training them up for so long. Evil geniuses, they never learn: keep it simple.

Connectivity: 

The Android Invasion and The Time of Angels / Flesh and Stone both feature a Doctor travelling with a single female companion, plus the inclusion of a semi-regular character first introduced with a previous Doctor.

Deeper Thoughts:

Double History. The Android Invasion is one of a rich seam of Doctor Who stories, from throughout its lifetime, that fall in to a particular category: rip-offs of Invasion of the Body Snatchers. This Doctor Who story - with its sinister versions of familiar people emerging from pods - is pretty blatant, but it's only one of many, many examples. A couple of classic monsters - the Autons and the Zygons - are wholly built around the duplication and substitution method cribbed from Body Snatchers, and a couple of others have dabbled (the Sontarans used their cloning tech to make a fake Martha in The Sontaran Stratagem, the Daleks made a robot copy of the Doctor in The Chase that even looked like him from some angles). In the lower monster divisions, the Chameleons were the first Body Snatcher types to appear in the series, and Axos had a go copying Bill Filer. Then there was Sharaz Jek making android copies of people in The Caves of Androzani, and the various android makers of Tara doing similar (in The Androids of Tara) and probably many more that I've forgotten.

Doctor Who loves a doppelgänger (oh yes, of course, I forgot the Gangers from The Rebel Flesh / The Almost People, I knew there were more!). There's a few obvious reasons why; it allows a regular actor to play someone different, and usually evil, to demonstrate their range, or prevent them getting bored. In the early days, this didn't require much plot reconciliation beyond just throwing in a massive coincidence. William Hartnell got to play his double the Abbot of Amboise in The Massacre, and Patrick Troughton Salamander in The Enemy of the World, with no need for any clever trickery on anyone's part; the characters just happened to look exactly like their respective Doctors. By the time of later original series examples - Tom Baker as Meglos, Peter Davison as Omega - this clearly wouldn't wash, so some technobabble about copying body prints or some-such was tossed in. 21st century Doctor Who allowed its star to flex his acting muscles only a couple of times, with Matt Smith playing a copy of the Doctor in the aforementioned Ganger episodes, and David Tennant becoming two subtley different versions of the Doctor in Journey's End. Tennant memorably also got to play John Smith, a completely different character, in Human Nature / The Family of Blood. But, as both characters occupy the same body in that story it's not quite the same, and is more like a character possessed (another trope Doctor Who loves to do) than a dopplegänger situation.

The other main reason for lookalikes appearing in Doctor Who is not so much arising from the plot as it is a quirk of casting on a long-running show: the 'haven't I seen you somewhere before' factor. In the 20th century, this was just one of those things and didn't warrant explanation or even comment for the most part. As mentioned above, Milton Johns played several guest roles on Doctor Who over the years without rationalisation in the script, as did Bernard Horsfall, Micheal Sheard, Philip Madoc and loads of others. No one batted an eyelid when this happened with regulars either: Peter Purves and Ian Marter played different characters before they became companions Steven and Ian respectively, and Jacqueline Hill played a different character later without the Doctor commenting that she was the dead spit of his old friend Barbara.  Even a Doctor (Colin Baker) was cast after having been in the series in a guest role the previous year. It's only with the post 2005 stories that it becomes necessary to hang a hat on this with some exposition: Eve Myles and Freema Agyemen's one-off characters were mentioned as being related to the regulars they later played. Peter Capaldi, cast like Colin Baker as Doctor after an earlier guest role, has picked the face deliberately to remind him to be kind or something. The only one I can think of that's never been explained is why Karen Gillan was in ancient Pompeii before becoming regular character Amy Pond. But as current showrunner Chris Chibnall has expressed a desire to bring Pond back it's not too late. Just as long as a plot tidying up some age old continuity can tempt Karen Gillan back from Hollywood paychecks and budgets, it can't fail! 

In Summary:

Unfairly overlooked - this is a lot of (silly) fun.