This rumbles on without much energy or conviction, with endless scenes of people wandering about, or K9 apparently floating across the rocky cave floor. The cliffhanger reprise features a shot of the Doctor fiddling with the sonic screwdriver that seems to go on forever and sets the scene for a sluggishly-paced episode where Alan Lake’s gurning, Welsh fury and Louise Jameson are the only people that look like they’re trying (the scene where Idas asks if he can travel with the Doctor and Leela is so stumblingly done it looks like improv). By all accounts this was a fairly unhappy serial to record. It’s barely much happier to watch.

Usually, episode by episode, classic Doctor Who is pretty entertaining. For 25 minutes a week, even the middle episodes of six-parters usually have enough incident and fun moments to be bearable. I griped about some of the rubbish effects and dialogue in The Invisible Enemy, but at least it had laughs, intentional or not. This is directed and performed through gritted teeth. It’s remarkable it got made at all, sure, but you wonder why they bothered.

What’s good about it? The floating about the middle of the planet is cute. Louise Jameson is putting in the hard graft, delivering lines like ‘that is the roof’ as Idas struggles to comprehend a sky full of stars, or ‘do not worry’ as she takes him by the hand. The Seers remove their black hoods to reveal identically-shaped gold hoods, which is Sontaran funny. Erm…

Next episode: Underworld – Part Four