Inspirations: The Hungry Earth / Cold Blood

This two-parter very much looks to the Pertwee era for its inspiration.

The Third Doctor was the first to encounter the Silurians, and then their marine cousins the Sea Devils (both of whom only ever returned once, opposite the Fifth in the underwhelming Warriors of the Deep). An appearance in the revived series was always on the cards - though we would have to wait another 12 years before we saw the Sea Devils again. 

The Hungry Earth / Cold Blood features another UK colony of Silurians, whose shelter has been disturbed by the activities of a scientific research project - the Wenley Moor cyclotron then, and a Welsh deep mining operation here.

In recognition of the naming controversy, the creatures are referred to as Homo Reptilia here. Their creator, Malcolm Hulke, had selected the name "Silurian" purely because it sounded good, and he thought - in the pre-internet era - that the era was a suitable one. He corrected this after the production team received letters about it, and had the Doctor rename them Eocenes in The Sea Devils.

Unfortunately this is also wrong. The Triassic to the Cretaceous were the eras of the large reptiles.

The Doctor attempts to prevent conflict and begin peaceful negotiations between humans and Silurians - just as he tried in the two Pertwee stories. As in The Silurians, one of the reptile people is a war-monger who undermines his efforts, and as in The Sea Devils, an aggressive human does the undermining.

This story at least ends with the Doctor setting up a future round of negotiations, when the time is right.

(Though there is no sign of human-Silurian co-existence in any future-set story).

An early design for the new Silurians was very much based on the originals. However, Steven Moffat decided to veto the third eye (supposedly because Davros already had a third eye that lit up...).

Sadly, we end up with a rather sub-Star Trek make-up. The masked versions have a similarity to Sea Devils.

The Silurian guns are based on the Sea Devils'.

Another obvious Pertwee inspiration is the energy dome which is set up to isolate the village. This clearly mirrors the heat barrier from The Daemons.

There's no trace of green ooze turning people in werewolves, but we've seen an experimental drilling project in Inferno.

A medical procedure harmless to humans but potentially fatal to a Time Lord, we have also seen in the Pertwee era - in The Mind of Evil.

Chris Chibnall was given the Silurians as a given, along with the idea of "we drill down to them - and they drill up to us". It was Moffat who decided that these Silurians should belong to another branch, to explain the changes.

In an interview, Chibnall described his intention as Passport to Pimlico meets Tremors. 

Passport to Pimlico (1949) is a classic Ealing Comedy, in which a district of London finds itself cut off, diplomatically and physically from the rest of the UK.

Tremors (1990) is a Kevin Bacon-starring comedy-horror about carnivorous subterranean creatures attacking an isolated desert town.

As far as the series' story arc is concerned, this was a key piece. At the conclusion we see the crooked smile crack, and Rory is first killed by Restac, then removed from time by it.

Amy forgets who he is.

The Doctor retrieves an item from it which proves to be debris from the TARDIS - revealing to him that his ship is at the heart of the explosion which is rippling throughout all of time and space.

Some aspects of this won't be resolved until Christmas 2013.

Next time: It's Richard Curtis, so expect to have your emotions manipulated. And Bill Nighy.