“Don’t just be obedient,” the Doctor tells companion Polly during The Macra Terror. “Always make up your own mind.” Good advice, and particularly Troughtony advice, if you ask me. This era of the program is all about the personal freedom to be different.

Think of the second Doctor’s most familiar adversaries, the soulless Cybermen (God knows I have recently, having randomed both The Wheel in Space  and The Invasion). They are an emphatic expression of uniform conformity, and what mankind might look like with all its quirks and peccadilloes removed. Think of The Faceless Ones, where the threat is that humankind might be taken over by the identity-less Chameleons. Think of The Web of Fear or Fury From the Deep where big, intangible bad guys zombify humans and delete their personalities. Think even of off-the-wall bedtime story The Mind Robber, where the ultimate threat is that a computer with ideas above its station that wants to enslave the minds of Earth. “Sausages!” the Doctor says on that occasion. “Man will just become like a string of sausages, all the same!”

The Macra Terror has a slightly different take on the loss of personal freedom, though. It’s not so much freedom of expression that its enslaved human population lacks (there’s too much music and dancing for that), but the lack of free will. Not so much a string of identical sausages as the right to be a sausage in the first place, I suppose.

In this story, the human inhabitants of a futuristic colony mine gas to feed their overlords, a race of giant crabs, the Macra. The humans don’t rebel because the Macra brainwash them as they sleep, and condition them into lives of toil alternated with a series of jolly, holiday camp activities. They sing and chant and hold dance competitions.

(Even for Doctor Who, the combination of threat and jollity is an odd juxtaposition. And it’s signposted in the first few minutes. The story opens with an extreme close up of a desperate man’s eyes and the thump of a heart beat, like some French new wave film. Then we cut to a marching band complete with an eye-watering electronic fanfare. It’s bizarre, arresting stuff.)

So successful is the Macras’ brainwashing that the humans never think to ask why they mine the gas, or why they never see their Controller in person (he always appears to them in a static, Big Brother style photo). They’ve been made passive, unquestioning slaves, spurred on by shrill motivational jingles piped in like musak. (This, combined with one of Dudley Simpson’s harshest electronic scores makes this story a listening experience to put your teeth on edge.)

And people being hypnotised into passivity is a theme that runs through all three of Ian Stuart Black’s Who stories, so it seems that the loss of free will was a prime concern of his. In The Savages one class of people sucked the life force out of another, leaving the victims passive nobodies. In The War Machines, a mad computer hypnotised people over the phone and forced them to make killer robots.

And although the terrible Macra have a similar modus operandi, they remain a mystery to the audience. We see their big crabby carapaces in the dark, and through portals, always obscured (or so it seems from the telesnaps). Their origins are similarly vague. Are they native to this planet or did they travel here? Why the elaborate scheme to oppress the humans? Surely any species clever enough to concoct and operate such a set up can mine its own gas. Or is it as prosaic a reason as that the Macra can’t operate the precise machinery required with those nasty old claws?

But we should never let plausibility get in the way of a Doctor Who story. I think the story’s concerns about brainwashing are more interesting. Because Who doesn’t do brainwashing. Mind control, yes. But the subliminal feeding of information to influence your behaviour and make you work against your allies? The Macra Terror’s certainly the only story that addresses it explicitly (although we can nod in the direction of The Keys of Marinus: The Velvet Web, and a couple of Malcolm Hulke stories). Here we hear the voices infiltrating the sleep of our heroes and see the results of it when companion Ben (played with consistent earnestness by Michael Craze) turns against his friends.

My limited reading about brainwashing indicates that it gained potency as an idea post the Korean War, with the notion that Korea and China both practiced brainwashing on US prisoners of war. So it makes sense that Ben, the TARDIS crew’s military man, is the one who succumbs here (also, Polly had her mind taken over in Ian Stuart Black’s last script, so it was probably time to mix it up).   The method used here is whispering instructions to the subject during sleep. It works a treat on Ben, but our other heroes – notably Jamie – avoid it.

I single out Jamie, because as I noted when randoming The Highlanders, Ben is on the way out and this is his last full story. Jamie gets the heroic young lead storyline, Ben gets the siding with the bad guys one. To me, it looks like a way of trialling what a Doctor-Polly-Jamie line up would look like, and sadly the answer for Ben is, just fine. It wasn’t meant to be as both Polly and Ben jump ship next story, but that line up is one of Doctor Who’s roads untravelled.

Ben’s brainwashing puts me in mind of The Manchurian Candidate, more often attributed as an influence on The Deadly Assassin. Specifically the 1962 film, where a young man is conditioned to commit treason and murder. It doesn’t go so far here, because the story demands that Ben break free of his conditioning and help save the day.  But still, Doctor Who at this time was often about the potential dangers presented by the modern world; it makes monsters out of limb replacement and threats out of holidays abroad. In this context, The Macra Terror seems to be suggesting that brainwashing of citizens is a plausible scenario: it could happen to you.

It may be going too far to suggest the Macras are a stand-in for communism, but then again… the loss of individuality, the loss of free will, the duped populace and a mind control technique allegedly practiced by communist governments and cribbing from The Manchurian Candidate… Put these things together and there’s certainly a reading to be made along those lines. If that’s too long a bow to draw we can at least say that The Macra Terror is rife with Cold War concerns.

But don’t take my word for it. As the Doctor says, always make up your own mind.

LINK to The Invasion. Both Troughtons of course, but both also feature underground threats and, you guessed it, mind control.

NEXT TIME… Santa’s a robot! We walk down the aisle with The Runaway Bride.