When I was a kid I absolutely adored dinosaurs. I had picture books, toys (not even smart toys, literally just solid, dinosaur-shaped chunks of plastic), I’d go mad for any film or TV that had them in. For my birthday one year my parents took me to the Natural History Museum in London to see the dinosaur skeletons. I could recite their names and tell you that the tyrannosaurus was the most ferocious dinosaur ever to walk the Earth. I was obsessed. They were the only thing that rivalled my obsession with Doctor Who. All of which is to say, if Invasion of the Dinosaurs had aired when I was six years old I would have been buzzing. It’s deeply unlikely I would have noticed or cared that the dinosaurs have all the mobility and liveliness of Liberace’s face. I would have been hooked. And I expect this would have been equally true for a big chunk of the target audience in 1974.

So while the monsters in this are unarguably pretty rubbish, it’s easy to look past them to see Sarah Jane Smith battling real-live dinosaurs. I still think this is one of the best ever concepts for a Doctor Who story. Largely it works because it isn’t overly reliant on the effects being amazing. Malcolm Hulke’s realistic assessment of what can be achieved means the dinosaur appearances are fairly thinly spread, and the time anomalies are also represented by the appearance of a medieval peasant in the present day. This, and the Doctor’s immunity to the accompanying time eddies that see the Brigadier and his men frozen, recall The Time Monster, but with more obvious relevance to the plot.

Hulke also inserts a conspiracy storyline connected to a mysterious ‘Operation Golden Age’, which rather brilliantly involves Mike Yates – up until recently little more than the Brigadier’s bag carrier, but between this and The Green Death promoted to undercover agent and now idealistic environmentalist, pining for foxes in Piccadilly and nightingales singing in Berkeley Square. The episode explicitly acknowledges Mike’s unlikely role as UNIT’s resident Romeo:

SARAH JANE: I’ll go and chat up that nice Captain Yates.
DOCTOR: Yeah, I’m sure he’d enjoy that.

But as Mike cannot prove a lover, he is determined to prove a villain, siding with shady Peter Miles and Martin Jarvis, and sabotaging the Doctor’s dinosaur stun gun. This pay-off to three years of failing to make an impression on Jo, or the audience (by all accounts Benton was the housewives’ choice) is very bold, and begins to tie in to the end of an era feel of Season 11.

Elsewhere, there are a couple of notable moments: the Doctor declares, ‘Miss Smith is presently acting as my assistant,’ formalising the ad hoc arrangement of The Time Warrior. Sarah looks vaguely surprised but seems quite happy with it. And there’s a faintly desperate comedy sequence of everyone bothering the Doctor when he’s trying to work (‘Go away!’ he tells Sarah, rushes to lock the door behind her then pulls the kind of exasperated face that went out with the advent of the Talkies when the Brigadier walks in through the other door).

Next episode: Invasion of the Dinosaurs – Part Three