Inspirations - Logopolis

Logopolis - the final story of Season 18, and the end of Tom Baker's lengthy tenure of the TARDIS.
When John Nathan-Turner took over as producer of Doctor Who, he would have been well aware of how difficult his star could be - having witnessed first hand the headaches Baker had given his predecessor. From the start he intended to make sure that this wouldn't be his experience. He would rein Baker in, stamping his authority on all aspects of the show, but ideally he wanted to cast a Doctor of his own. Baker himself had been ill, and contemplating moving on anyway. He could see the writing on the wall, and guessed what JNT wanted, so he offered his resignation. Later, he expressed dismay at how quickly this was accepted.
Script editor Christopher H Bidmead had experienced a troubled year on the show - from finding the script cupboard bare on his arrival to having to extensively rework other people's material. He decided to leave. An interim script editor was identified - Anthony Root - to take over from him on a short term secondment. However, he wouldn't be starting until the beginning of Season 19. Bidmead had championed the writers John Flanagan and Andrew McCulloch, who had already contributed Meglos. They were invited to write a second story which would form the season finale. What they came up with was a story which is known as "Project 4G" or "Project Zeta-Sigma".

This would form part of another trilogy which would bridge the regeneration of Tom Baker into Peter Davison, JNT's choice for his new Doctor. The trilogy would comprise The Keeper of Traken, "Project 4G", and a story called "Day of Wrath" - which ultimately became Four to Doomsday.
"Project 4G" ran into problems and was moved to third place in the trilogy, becoming the new Doctor's debut story.
Bidmead himself stepped in to write the final story of the season, whilst still holding the script editor post.
He decided that he wanted to explore the TARDIS more. It generally got the Doctor from adventure to adventure, but it was a very long time since it had been the focus of a story. Bidmead was also inspired by his interest in computers. He had already named a piece of equipment in Warrior's Gate after his own machine, and could no doubt take it apart and put it together gain. One thing he noticed was that he could see how much memory was being used as an application ran, and where on the machine it was. He got the phrase "block transfer" from this. Likewise bubble memory, and numerical registers. The Monitor (a computer component) tells the visitors to Logopolis that his people work in registers, making their calculations in their heads and only seldom using technology - in this case the machinery needed to run their copy of the Pharos Project so that it will keep the CVEs open and prevent the destruction of the universe. The name 'Logopolis' derives from 'city of words', as the Logopolitans intone their calculations. Their settlement, from the air, looks like a giant brain.
The Pharos Project is based on the SETI Project - the Search for Extraterrestrial Intelligence. The name, as Tegan points out, comes from the lighthouse at Alexandria, which was destroyed by a fire in antiquity.

As far as we know, Bidmead came up with the idea of the TARDIS within a TARDIS in the opening episode, but you'll recall that Barry Letts was still acting as exec-producer at this time, and no doubt he would have reminded him that this had been done before in one of his own stories - The Time Monster - where once again it is all down to the Master and the Doctor having their TARDIes in the same place at the same time. (This would be Letts' last involvement with the series as, from Season 19 onwards, it was felt that JNT could manage on his own).
A running theme throughout this season has been that of entropy, and it features prominently in this story. According to the second law of thermodynamics, entropy always increases over time. If you make a cup of tea, it will lose heat the longer it sits there. The simple definition is that it is the amount of energy which is unavailable to do work. It can also be a measure of randomness or uncertainty. In Logopolis, we learn that the universe has long passed the point of heat death, where there is no more energy left in its closed system, so the Logopolitans have opened the system up to external sources of energy - bubble universes such as E-Space. Access to these is through the CVEs. When the Master upsets the running of the planet, the CVEs begin to close. No more energy is able to transfer, so the universe begins to die.

Logoplis sees the introduction of a new female companion to accompany Adric, and who will help bridge the regeneration. This is Tegan Jovanka. JNT was offered the two names to choose from, and elected to use both, making Jovanka (a Slavic christian name) the surname. It has always been claimed that the decision to make her an Australian air hostess was a means to tempt Quantas to give the production team cheap flight tickets, as there was a plan afoot at this time to enter into a production deal with the Australian Broadcasting Corporation to film a couple of episodes "down under". ABC declined the offer, although the BBC pursued it for a time. JNT made sure that Tegan was a BBC copyrighted character, as he also decided to bring back Nyssa and have her carry on as a regular - leading to the "overcrowded TARDIS" of the Peter Davison era. As mentioned last time, as Nyssa had been created just for his story, Johnny Byrne was paid for every story in which she appeared.

Throughout the story, the Doctor keeps seeing a mysterious white figure, referred to as the Watcher. It was hoped that viewers might think that this was the Master - even though we had already seen him "regenerate" into Anthony Ainley. The Watcher proves to be a version of the Doctor himself - an interim entity from between the incarnations. We had already seen something similar with Cho-Je in The Planet of Spiders, the last time the Doctor regenerated. There, the younger monk was a future projection of the Time Lord K'anpo - the form he would later regenerate into. There are other Pertwee references with the Master's use of the Tissue Compression Eliminator - first seen in his debut story Terror of the Autons, but not used again until The Deadly Assassin. We also have the radio telescope setting. The Master made his debut at just such an establishment, and the Ainley version also has one as a backdrop for his first proper story.
Next time: Bidmead gets called back and writes the debut for the new Doctor, basing it partly on a picture which really annoyed JNT...