I wonder when it was during the production of Season Five, that someone on the production team counted how many ‘base under siege’ stories they done. Blimey, there are a lot of the buggers. It’s no wonder that by Season Six, they wanted to try something different.

It’s a wild old thing, Season Six. One minute they’re heaping scorn on a world of pacifists, the next they’re taking an excursion into a story book, the next it’s James Bond with Cybermen. The series really did take a sudden left turn away from isolated scientific outposts, truculent commanders and lashings and lashings of foam.

I think writer Robert Holmes noticed, because in his debut story for Doctor Who he inverts the standard Season Five structure, by placing the alien Krotons’ crystalline base (ladies and gentlemen, a big round of applause for Miss Dinah Trope!) inside the humanoid Gonds’ city, and have people constantly trying to break in to get at them. It’s the Krotons’ base which is under siege. Nice work, Mr Holmes. You’ll go far.

The Dynatrope sits like a tumour in the heart of the Gonds’ city. The Gonds are educated by teaching machines provided by the Krotons, and every so often, the two smartest swots are given fancy cloaks and sent inside the Dynatrope, never to return.  This is the state of affairs that the Gonds have put up with for thousands of years and the reason why they’ve never rebelled is that the Krotons have edited out all the information which might have helped them put two and two together.

“It’s a kind of self-perpetuating slavery,” muses the Doctor (the Trought, in playful form). He’s right, but it’s also a throwback to one of this era’s other themes, of whole races of people kept subordinate by being deliberately kept in ignorance. Think of the hapless colonists of The Macra Terror, or more recently the subterranean dupes of The Enemy of the World. I’ve written before about how this era of the show is often about threats to personal identity, but this story is about the ability to enslave through manipulation rather than the threat of physical violence.

But as is so often the case, the arrival of the Doctor is a catalyst. Hotheaded Thara (Gilbert Wynne) leads an attempt to vandalise the teaching machines. In 1968, students rioted against authority on the streets of Paris, so we can see the mirroring of real life events. But it’s not an analogy Holmes keeps up for long. In plot terms, the machines are needed to facilitate the Doctor and Zoe’s (Wendy Padbury) entry into the Dynatrope. They answer a few sums on the machines and are declared ‘high brains’ so are given access.

In fact, our heroes’ brains are so high that they cause the reanimation of the Krotons themselves, creatures who get less impressive the further you get away from their heads (which are solid angular creations on broad metallic shoulders, which unfortunately give way to plastic tubing arms, which unfortunately give way to smooth shiny foot skirts). They emerge out of bubbling tanks, like some Hammer horror off a mad scientist’s bench top. Holmes’ penchant for the gothic gets an early workout here (Holmes will pull off a similar tanky reanimation a few stories later in Spearhead from Space). When they speak, it’s with booming South African accents, which, as The Sontaran Experiment will tell you, is the go-to accent for strange and alien. We never get monsters which speak with French accents, more’s the pity. Or Swedish. Or Dutch. (But it may not be too late. The campaign starts here.)

But despite these glimmers of interest within The Krotons, the rest of it is a shabby affair. Not just because the sets and props look terribly creaky (perhaps they spent all this story’s budget on The Invasion) but the script is nowhere near as witty and well rounded as we’ll learn to expect from Holmes. The supporting cast members are all fairly unimpressive, but it’s not like they’re helped along by any memorable dialogue or consistent characterisation. A howling example comes at the end when head Gond Selris (James Copeland) sacrifices himself to get a bottle of acid to Zoe and the Doctor. His death goes uncommented by everyone, including his own son, that firebrand Thara. You really are a forgettable character if your own son can’t be arsed to mourn your death.

*****

It’s easy to write The Krotons off as tacky, uninspiring addition to Troughton’s era. But in some ways, it’s a story which has continually punched above its weight. It really shouldn’t exist at all; it was commissioned as a fall back option in case any other stories had to be shelved. Which is exactly what happened – imagine how awful The Prison in Space must have been if they thought making The Krotons was a better option.

But it’s wasn’t to be so easily forgotten (try as we might). It gained prominence by its inclusion in the Five Faces of Doctor Who repeat season in 1981, by virtue of being the only surviving four part Troughton story at that time. For many fans, this makes The Krotons their first taste of Troughton’s era, and so I think it’s gained a special place in people’s memories, if not affections. (It kind of happened in Australia too, when in 1986, we suddenly got repeat screenings of this story and The Mind Robber). And that’s not so bad, because although the story’s pretty ordinary, Troughton, Zoe and fellow traveller Jamie (Frazer Hines) are on good form trying to liven things up, so at least an impression of their joint chemistry had been formed by The Krotons’ encore viewing.

Even more recently, we haven’t quite been able to give up on this story. Lawrence Miles’ terrific Eighth Doctor novel Alien Bodies, turned the doddery Krotons into Dalek killing predators. And Big Finish Productions, those champions of long forgotten B-listers of Whos past, conjured up a Return of the Krotons for the Sixth Doctor. We can’t quite seem to let these also-rans go.

It’s in part because we’ve grown to admire the work of Holmes so much through his subsequent, more interesting Doctor Who stories. We want to go back to this, his earliest, formative work and re-examine it, to find in it some speck of genius which has been hidden from us for so long. Surely Holmes, that master of Who, hid something up his sleeve which we can find in retrospect. Sadly, though, I don’t think he did.

*****

Mad old Season Six. What did it have in store for us next? Why, The Seeds of Death, with lumbering monsters, an isolated scientific outpost, a truculent commander and lashings and lashings of foam.

Ah well, maybe after the terror of The Krotons, there’s still some comfort to be found in a base under siege.

THING I COULDN’T FIT ANYWHERE ELSE: All the episodes start with a shot of a circle, or some vaguely round shape. What’s that about then?

LINK TO Castrovalva: actually it’s about the same as for The Enemy of the World – a small community kept in ignorance of the true shocking nature of their world.

NEXT TIME: Burn with me! We’ve got 42 minutes till we fall into the sun.