The episode title – The Valley of Monsters – would no doubt have raised the audience’s expectations, so possibly that was why our first sight of the monsters – stock footage of animated flying reptiles – provided the previous episode with its cliffhanger.  At least that way most people would know what they were going to get here.

This instalment was especially fascinating since it was used for an academic study into children’s viewing habits and opinions.  To this end, eight deliberate production mistakes (in addition to any inadvertent ones) were introduced into the episode.  Several groups of children were then shown the episode, with their interest levels and comments closely monitored.

It was discovered that young children were just as demanding and critical as any other viewing group.  As producer Sydney Newman later noted. “The most important thing we learnt is that if anyone thinks a young audience can be fooled or won sloppily or ‘on the cheap’ he is sadly mistaken”.  No doubt these lessons would have been taken on board when Newman moved to the BBC and initiated the creation of Doctor Who.

I have to confess that none of the production mistakes were particularly apparent.  Maybe I was just unobservant or possibly too wrapped up in the story?

Our heroes manage to escape the dangerous stock footage flying reptiles and they then proceed to make their way through the forest on the long trek back to the rocket. The forest clearing, where they pitch up for a rest, is pretty bare but a later sandstorm is effectively done.

There’s more animated stock footage (a Tyrannosaurus Rex battles a Stegosaurus as our heroes look on in awed wonder). The models are a little small and grubby, but the dramatic music – and acting – sells the illusion resonably effectively.

Latest Kisswatch update – Conway and Mary enjoy a passionate kiss on the lips. Hurrah! Marriage doesn’t seem to be on his mind though, unless he’s being very subtle. But he does ask if they can work together when they return to Earth, so maybe this is the first step in his plan to woo her.

We return to Buchan Island for the first time since the opening episode. The Russian rescue rocket has nearly reached Venus, but with no evidence that Conway and the others are still alive, it’s likely to just turn around and go home.

Malcolm Hulke tended to pepper his Doctor Who scripts with political, moral or environmental messages. Pathfinders never really went down these routes but this episode – for example, Wilson sees a chance to make a great deal of money by plundering Venus of its plentiful diamond supply – does supply us with a vague message.

It does mean that Wilson, up until now a level-headed chap, suddenly turns into an avaricious monster. This moment quickly passes, but the discovery of uranium is another flashpoint. Wilson paints a vision of Venus as a colonised world, its natural reasources mined for the benefit of Earth (America), a prospect which disgusts Brown. Wilson tells Brown that “you can’t stop progress”.

It’s interesting thar Brown’s desire not to see Venus strip-mined isolates him from the others. But when the way back to the rocket is blocked by raging forest fires, he gleefully tells them that nobody will ever leave the planet. Instead, they’ll become the first of the new Venusians ….