Editing Logopolis (section)

==Production==
===Casting===
{{multiple image |total_width=350 |perrow=4 |caption_align=left
| image1 = Peter Davison 2016.jpg
| caption1 =[[Peter Davison]] (The Doctor)
| image2 = Janet Fielding, Baltimore 1987 2.jpg
| caption2 = [[Janet Fielding]] (Tegan Jovanka)
| image3 = Sarah Sutton.jpg
| caption3 = [[Sarah Sutton]] (Nyssa)
| image4 = Anthony Ainley, Baltimore 1987 2.jpg
| caption4 = [[Anthony Ainley]] (The Master)
| footer = Actors joining the regular cast of ''Doctor Who'' in ''Logopolis''
}}
The serial introduces Janet Fielding in the role of Australian trainee [[flight attendant]] Tegan Jovanka. Nathan-Turner conceived the role in collaboration with Bidmead, with the intention of introducing a younger female character who would display a superficial self-assurance masking inner vulnerability, without returning to the stereotype of screaming female companions of earlier serials. Brisbane-born Fielding had lost some of her native [[Australian accent]] since emigrating to the UK in 1977, but revived her accent to audition successfully for the part.{{sfn|Anghelides|Richards|1994|pp=6 & 9}} Nathan-Turner initially wished to reintroduce a former companion to provide continuity for viewers following Baker's regeneration, but created Tegan when [[Elisabeth Sladen]] ([[Sarah Jane Smith]]) and [[Louise Jameson]] ([[Leela (Doctor Who)|Leela]]) both declined to return for the duration of [[Doctor Who season 19|season 19]].<ref>{{cite AV media notes |last1=Pete |first1=McTighe |author-link1=Pete McTighe |date=2019 |chapter=Logopolis |title=''Doctor Who'': The Collection Season 18 |publisher=[[BBC Studios]] |page=23}}</ref>

Two cast members returned from the previous serial, ''[[The Keeper of Traken]]'': Sarah Sutton reprised her role as Nyssa, joining the TARDIS crew as a companion; and Anthony Ainley had his first full exposure in the role of the Master, a part he would continue to play for eight years. Outwardly, Ainley's beard and dark costume suggested close continuity with [[Roger Delgado]]'s portrayal in the early 1970s, but Ainley imbued his part with a greater focus on revenge and blackmail.{{sfn|Anghelides|Richards|1994|pp=4,12-13}}

The part of the mysterious Watcher was played by Adrian Gibbs; his part was left uncredited in order to foster a belief among fans that Peter Davison had played the role wrapped in white fabric. In fact, Davison's only appearance was during the final seconds of Part Four as the newly regenerated Doctor, for which he attracted a full actor's fee.{{sfn|Anghelides|Richards|1994|p=4}}

===Filming===
[[File:Jodrell Bank (4736511224).jpg|thumb|The BBC was unable to film on location at [[Jodrell Bank Observatory|Jodrell Bank]], and a scale model was used instead. Drone shots of the telescope were included in the 2019 Blu-Ray DVD release]]
For the outdoor scenes in Part One, in which Doctor materialises the TARDIS next to an actual [[police box]] on Earth, the production team had initially planned to [[Location shooting|film on location]] in a [[layby]] on the [[A1 in London|Barnet Bypass]], in the outskirts of [[North London]]. By the 1980s, police boxes had been obsolete for many years, but one of the last surviving boxes in Britain was still standing here, and it was intended to film the TARDIS prop standing next to the real police box. However, shortly before filming was due to take place, the production team discovered that the Barnet police box had been vandalised and subsequently demolished. Filming was re-located to a layby on the southbound side of the [[A413 road|A413]] [[Amersham]] Road near [[Denham, Buckinghamshire]]. An older TARDIS prop which had last been used in [[Doctor Who season 17|season 17]] was brought out of storage and assembled on location to stand in for the real police box. Today, the [[M25 motorway|M25]] bridges the road where the scene was filmed.<ref>{{cite web |title=BBC - The Fourth Dimension: Logopolis |url=https://www.bbc.co.uk/programmes/articles/1v9MWZyM2QD2hLbwHT6LBCb/the-fourth-dimension |website=bbc.co.uk |publisher=BBC |access-date=17 January 2025 |archive-url=https://web.archive.org/web/20170316002822/https://www.bbc.co.uk/programmes/articles/1v9MWZyM2QD2hLbwHT6LBCb/the-fourth-dimension |archive-date=16 March 2017|url-status=live}}</ref>{{sfn|Burk|Smith|2013|p=213}}

It had originally been intended to film the outdoor Pharos Project scenes in Part Four on location at the [[Jodrell Bank Observatory|Jodrell Bank]] [[Lovell Telescope]] in Cheshire, but this was precluded by budgetary constraints. Instead the exterior scenes were filmed at the BBC's receiving station in [[Crowsley Park]], and [[miniature effect]] shots were created using a [[scale model]] of a radio telescope. The scenes in the structure of the telescope were shot on [[Stage lighting|lighting gantry]] in the [[Top of the Pops]] studio at [[Television Centre, London]].{{sfn|Anghelides|Richards|1994|p=6}}<ref name="bbcstudios-blu-ray">{{cite web |title=Press Releases: Revisit Everyone’s Favorite Classic Era Doctor In Doctor Who: Tom Baker Complete Season Seven For The First Time On Blu-ray March 19, 2019 |url=https://www.bbcstudiospressroom.com/press/revisit-everyones-favorite-classic-era-doctor-in-doctor-who-tom-baker-complete-season-seven-for-the-first-time-on-blu-ray-march-19-2019/ |website=www.bbcstudiospressroom.com |publisher=BBC Studios |access-date=12 January 2025 |archive-url=https://web.archive.org/web/20240909123341/https://www.bbcstudiospressroom.com/press/revisit-everyones-favorite-classic-era-doctor-in-doctor-who-tom-baker-complete-season-seven-for-the-first-time-on-blu-ray-march-19-2019/ |archive-date=9 September 2024 |date=19 March 2019 |url-status=live}}</ref><ref name="uom-jodrell">{{cite web |title=When Doctor Who came to Jodrell (and UoM’s other sci-fi hits) |url=https://www.mub.eps.manchester.ac.uk/science-engineering/2018/12/12/when-doctor-who-came-to-jodrell-and-uoms-other-sci-fi-hits/ |website=Science and Engineering |publisher=[[University of Manchester]] |access-date=12 January 2025 |archive-url=https://web.archive.org/web/20220524083000/https://www.mub.eps.manchester.ac.uk/science-engineering/2018/12/12/when-doctor-who-came-to-jodrell-and-uoms-other-sci-fi-hits/ |archive-date=24 May 2022 |date=12 December 2018 |url-status=live}}</ref>{{sfn|Anghelides|Richards|1994|p=6}}

Incidental music in the serial was composed by [[Paddy Kingsland]], and includes [[leitmotif]]s for Logopolis and the Watcher. In Part Four, an excerpt from [[Symphony No. 8 (Schubert)|Symphony No. 8]] by [[Franz Schubert]] is heard playing on the technician's headphones  in the Pharos Project control room.{{sfn|Anghelides|Richards|1994|p=18}}<ref name="pac">{{cite web |title=Dr. Who Programme-As-Completed |url=https://www.bbc.co.uk/doctorwho/classic/episodeguide/pasb/logopolis.pdf |publisher=BBC |archive-url=https://web.archive.org/web/20150208015638/https://www.bbc.co.uk/doctorwho/classic/episodeguide/pasb/logopolis.pdf |archive-date=8 February 2015 |date=28 February 1981 |url-status=live}}</ref>

===Titles===
The closing titles sequence was recompiled with Tom Baker's face removed from the closing credits of Episode 4. The same opening and end title sequence and arrangement of the theme music was used for the following story, ''[[Castrovalva (Doctor Who)|Castrovalva]]'', and next three seasons, but was altered to include Peter Davison's face. Episode 4 of this story was the last time, for the next 24 years, the lead character was listed in the credits as "Doctor Who" (thus making it the only time Peter Davison was credited as "Doctor Who"). Beginning with the next story, ''Castrovalva'', until the series's cancellation in 1989, the character was credited simply as "The Doctor". The [[Doctor Who (film)|1996 television film]] did not have an on-screen credit for the [[Eighth Doctor]], but listed the [[Seventh Doctor|Seventh]] as the "Old Doctor". The [[Doctor Who (series 1)|2005 relaunch]] returned the credit to "Doctor Who", and then again to "The Doctor" in "[[The Christmas Invasion]]" (at the request of [[David Tennant]]). Also, Episode 4 was the first to credit two actors as "Doctor Who" or "The Doctor" when a regeneration scene was involved. It also happened at the end of Episode 4 of ''[[The Caves of Androzani]]'' (1984). In both instances, Peter Davison was billed second.{{cn|date=January 2025}}

===Outside references===
According to Christopher Bidmead, the Logopolitans employ a [[hexadecimal]], or base-16, numerical system, a real system commonly used in computer programming. When Adric and the Monitor read strings of numbers and letters, the letters are actually the numbers between 10 and 15, expressed as single digits.{{cn|date=January 2025}}