Inspirations: Kill The Moon

"As far as the science goes, that's not something I worry about"... So said Peter Harness of his first submission for Series 8, and never were truer words ever spoken as far as Doctor Who is concerned - at least not until RTD2 returned.

The main inspiration for this story was Moffat's idea of a situation which would see Clara's relationship with the new Doctor challenged, such that she would come to question if she really wanted to be around him. Harness had contributed a story titled "When We Weren't There", but when this was rejected it was he who came up with the absurd notion that the Moon was really a gigantic egg that was about to hatch.

After broadcast, many thought this episode an allegory about abortion, but Harness denied that this was thought of at the time. He said that if he wanted to write about that subject then he would have covered it as a proper contemporary drama.

The story was originally planned for Matt Smith's Doctor, with the then intended companion being a Victorian governess. She would be accompanied by one of her young charges - which is why we have Courtney from Coal Hill School instead.

It was intended from the start to begin as a base-under-siege horror story, and the writer was concerned it might be too scary for a family audience - but Moffat advised him to "Hinchcliffe" it to the maximum.

The Philip Hinchcliffe era is characterised for its Gothic horror trappings, thanks in part to the script editorship of Robert Holmes.

Giant spiders were chosen as the monster as so many people are arachnophobes. 

The episode would then concentrate more on the relationship between the Doctor and Clara. Moffat wanted this to be damaged by events, with no reconciliation between the pair at the conclusion.

At a crucial point in the narrative, the Doctor was to abandon Clara to make a decision on her own. Harness and Moffat were considering the more alien natures of the First and Fourth Doctors - the two they felt often exhibited the least empathy with human beings. The First took a very long time to warm to Ian and Barbara, and often insisted on getting back to the TARDIS and leaving others to sort out their own problems, and the Fourth could also act this way - such as when he insisted that the Antarctic base personnel carried out the surgery needed to save their colleague from becoming a Krynoid in The Seeds of Doom - "You must help yourselves".

At one point in this story the Doctor states that Earth isn't his home - just as he had told Sarah in The Pyramids of Mars.

The Blinovitch Limitation Effect (introduced by Barry Letts and Terrance Dicks in the era of the Third Doctor to get round potential temporal paradoxes) was going to be a big element of the story originally. Courtney was to have changed her ways following the events on the Moon and would go on to marry the scientist Blinovitch, after first meeting her future self. The future Mrs Blinovitch would cause Courtney to become the future Mrs Blinovitch.

On deciding to film the Moon surface material in the volcanic landscape of Lanzarote, a draft title of "Return to Sarn" was concocted, making fans think this a sequel to Planet of Fire, which had also been filmed there.

The story is set in the year 2049. It had to be before the year 2070 so that Courtney could become the first female to set foot on the Moon - as Polly was there in 2070 in The Moonbase.

This episode means that all of the lunar-set stories like that and The Seeds of Death have to now be set on the new Moon left behind at the conclusion of this story.

In that Ice Warrior story, the human race had virtually given up on space travel - which is what is also happening here - though it's generally accepted that the events of The Seeds of Death come later than those of The Moonbase.

The Doctor gives Courtney one of his rules as "no hanky-panky in the TARDIS" - a phrase often used by producer JNT regarding the younger Fifth Doctor travelling with two young women (Tegan and Nyssa).

Peter Capaldi asked for a yo-yo identical to the one Tom Baker had used - such as when he tested the gravity in The Ark in Space. (His daughter's boyfriend showed him how to use it).

The Doctor spots a primitive Bennett Oscillator - first mentioned in that same Tom Baker story, named after its director Rodney Bennett.

The Doctor got his Sanctuary Base 6 spacesuit in The Impossible Planet / The Satan Pit, but it is never explained where he got another pair of identical suits - considering that the base was subsequently sucked into a Black Hole.

Next time: Agatha Christie meets Hammer Horror, in a story which has its origins in a throwaway line from The Big Bang...