The Tenth Planet (TV story)

The Tenth Planet was the second serial of season 4 of Doctor Who. It was the final chronological appearance of William Hartnell as the First Doctor and introduced Patrick Troughton as the Second Doctor in the final moments of part four.

Due to the fact that The Smugglers was the final story in season 3's production block, however, The Tenth Planet was actually the first story produced in this season; from a production standpoint, this was William Hartnell's only contribution to season 4. It also introduced the Cybermen, who would become a longstanding enemy of the Doctor.

The Tenth Planet was a major historical turning point for the Doctor Who series by employing a new concept that would come to be known as regeneration. This plot mechanic has contributed to its long run on television. Likewise, it introduced the idea the Doctor has multiple incarnations and can regenerate to coincide with the departure of an actor playing an incarnation to avoid cold transition from one actor to the next.

Hartnell returned to reprise the role of the First Doctor one final time in 1972-73's The Three Doctors for the opening of the tenth anniversary season of Doctor Who.

Currently, the fourth and final episode of this serial remains missing from the BBC film archive, with only the regeneration sequence and various other short clips existing intact. However, the missing episode has been carefully reconstructed in an animated format for the DVD release in 2013, and the 2017 story Twice Upon a Time recreated parts of the missing episode for its opening sequence.

Synopsis
Many years ago, Earth's twin planet, Mondas, drifted away to the edge of space. Its inhabitants grew weak, so their scientists created spare parts for their bodies. Limbs and organs were slowly replaced by metal and plastic. Emotions were removed. The Cybermen were born.

The Doctor's TARDIS lands at the Snowcap space tracking station in Antarctica in December 1986. A routine space mission starts going wrong. When the base personnel's suspicions are roused, the Doctor informs them that the space capsule is being affected by the gravitational pull of another planet — a tenth planet in the Solar system.

The loss of a routine space mission and the appearance of that planet in the sky herald the arrival of the Cybermen, who are intent on the destruction of the Earth and the conversion of all humans into Cybermen. Ben and Polly fight to save the world, but it is a battle that may be the Doctor's very last.

Episode 1
The Snowcap space tracking station based on the South Pole is monitoring the launch of the manned Zeus IV atmospheric testing probe as it goes into orbit. The ship is manned by two pilots, Schultz and Williams.

The Doctor, Ben and Polly materialise outside the underground bunker of Snowcap and are soon spotted by men watching the surrounding areas through a periscope. Men are scrambled out to collect the strangers. The Doctor, Ben and Polly willingly enter Snowcap.

Inside Snowcap the Doctor, Polly and Ben are interrogated. General Cutler is sent for and responds hostilely to the strangers. Cutler decides to put them in the observation room until he has time to deal with them later. Once there, the Doctor notices a calendar on the wall saying it is December 1986. Ben is disappointed he won't be able to meet up with his ship but seems more interested when he discovers that space travel is the norm. This conversation is interrupted by a distress call from the Zeus IV space capsule which has been drawn off-course by an unknown force that drains the energy.

The pilots of Zeus IV explain that it is nowhere near the destination in which they would expect to be. Observing their location, Schultz sees another planet. Williams confirms this and says it seems to lie between Mars and Venus. Their state is also brought into confusion by the fact that the communication to Snowcap is weakened and their fuel is dropping much faster than normal.

Observing the crisis, the Doctor announces that he believes he knows the cause of the problems. He is not listened to but gives a piece of paper to Doctor Barclay. Snowcap sights the new planet before they receive the call from Zeus IV saying their fuel has reached 20% — Barclay says they should attempt to come down.

Schultz and Williams attempt to land, but they have no control over their descent as the new planet is affecting their gravitational pull.

Exasperated, Barclay goes to the Doctor for advice. The Doctor looks at a screen with the planet on it and observes that it is identical to Earth — down to the landmasses. The Doctor asks Barclay to look at the piece of paper that he had given him, and Barclay is astounded to read that the Doctor had predicted this phenomenon before they had even seen it. The Doctor tries to explain how he knew this, saying that millions of years ago there was a twin planet to Earth. Before he can go into any more detail, Cutler storms out, saying, "This is ridiculous." When alone, the Doctor explains to Ben that he fears this means invasion.

Cutler speaks to Mr Wigner, the Secretary-General of International Space Command, and informs him of the new planet as well as the strangers. Wigner demands that they be interrogated immediately.

Cutler storms in and demands the truth from the Doctor; he suspects him of being involved in this mystery. He sends Tito, the sergeant and Joe out to search the TARDIS.

The three men scramble to the TARDIS. Before they can get out, a mysterious ship lands on the surface of the South Pole. Unable to open the TARDIS, the sergeant sends Tito and Joe back to get a welder. Whilst alone, he is approached by a robotic creature who kills him with a blow to the neck. When Tito and the other soldier return, the creature is disguised in the sergeant's clothes. When he turns to reveal himself, two more robotic creatures appear and kill the two soldiers with blows to the neck. The three creatures loom over their victims.

Episode 2
The Doctor reasserts his belief that there will be visitors to Earth from the mystery planet but is pooh-poohed by Cutler. Cutler speaks to Zeus IV and promises the pilots they will be brought back safely.

Outside Snowcap, the robots disguise themselves in the clothes of their now-dead victims.

At International Space Command, a powerless Wigner is forced to watch the news to learn about the mystery planet as communications have been severed with Snowcap.

While everyone is distracted by their efforts to land Zeus IV safely, the alien invaders enter the base, killing a soldier who tries to disable them on the orders of Cutler. The base personnel and Polly plead with the creatures to allow them to save the lives of the Zeus IV crew, but the aliens proclaim that the lives of the humans are irrelevant to them. They reveal that they are known as Cybermen and were once like human beings. They lived on the planet Mondas, twinned with Earth. As Mondas drifted off into space, cybernetic scientists gradually replaced their bodies with mechanical parts and eliminated the "weaknesses" of illnesses and emotions from their brains. Cutler presses a panic button alerting International Space Control to an emergency. International Space Control gets in touch with Cutler, and the Cybermen order Cutler to inform them that it was a false alarm; Cutler refuses and is rendered unconscious by the touch of a Cyberman. Barclay is approached to do the same and refuses until the Cybermen threaten to destroy the computers that would help Zeus IV to land. Barclay yields, stating it as a fault. Once this has been done, the Cybermen inform Barclay it is impossible for the astronauts to return as Mondas' gravitational force is too close. As the Cybermen begin the process of securing Snowcap, Ben plans their escape. Seeing a gun left on the ground by the dead soldier, he picks it up but is soon spotted by a Cyberman. The gun is removed and bent in the Cyberman's grip, and Ben is removed and imprisoned in a projection room.

The Cybermen allow the Snowcap personnel to contact Zeus IV, but it is too late to save them. The ship is dragged further away from Earth by the new planet and explodes.

The Cybermen demand information on Earth and explain that Mondas' energy reserves are becoming exhausted; they intend to use all of Earth's. It is currently absorbing energy from Earth and will soon destroy it. When Polly asks if they plan to kill all of humankind, the Cybermen reveal they propose to take all humans back to Mondas.

Ben, who has been looking for a weapon, rigs up the projector to blind his Cyberman guard. He baits the Cyberman into the room. After the Cyberman is blinded, he steals the Cyberman's weapon and kills him. He seems to be affected by this death.

Ben sneaks back into the tracking room and hands the cyber-gun to the revived Cutler, who kills the remaining two Cybermen. Cutler contacts Secretary-General Wigner at Space Command HQ in Geneva and informs him of the attack. Wigner alerts all military bases and informs them that his son, Lieutenant Terry Cutler, was sent on a mission to rescue the doomed Zeus IV and, in turn, is now trapped in orbit.

As Cutler makes plans to secure Snowcap from further Cyberman invasions, including the use of anti-aircraft missiles, the radar technician announces that a fleet of spacecraft have been detected. They are approaching Earth.

Episode 3
Apparently suffering from exhaustion, the Doctor collapses and is taken to the crew quarters to rest. Cutler makes contact with Zeus V.

Ben and Polly accompany the Doctor to his quarters. Ben checks his pulse and says he seems fine. Polly remarks that he seems "worn out".

Cutler decides it is time to take the fight to the Cybermen. He intends on destroying Mondas with a Z-bomb — a series of nuclear bombs that are placed at strategic points around the world. He rings the International Space Centre. Secretary Wigner at Geneva refuses permission, but Cutler rephrases his question asking if he can do anything he deems suitable in order to destroy the Cybermen. Wigner agrees to this, and Cutler takes this as permission to use the bomb. Ben and Polly argue against using the bomb. Ben says the Doctor believed that Mondas will destroy itself anyway when it absorbs too much energy. Cutler does not appreciate this intervention and confines Ben to the same quarters in which the Doctor is resting. Before he leaves, he implores Polly to try to convince Barclay to call off the attack.

When Ben arrives at the quarters, he tries to rouse the Doctor, to no avail. However, he soon finds a vent that he begins to loosen with his penknife.

Dyson and Cutler fuse the bomb. Cutler admits he is scared by what he is about to do but feels that he has no choice. When he returns to the control centre, he is concerned to hear that they have lost contact with Zeus V. Polly talks to Barclay, who admits he is reluctant to launch the bomb, citing the radiation caused by the exploding planet which would cause great loss of life on Earth. Polly suggests they rig the bomb so that it doesn't explode. Their plans are interrupted by Cutler, who explains they are to wait for the Cybermen to land, and then they will destroy them with their own weapons. Barclay and Polly sneak away to find Ben. Barclay explains that he would need to go through the vent to reach the bomb and tells Ben how to sabotage the rocket to prevent it from reaching Mondas. As Ben leaves, the alarm to signal the arrival of the Cybermen sounds.

The Cybermen land and are immediately mowed down by the hidden soldiers wielding the Cybermen's weapons. The soldiers collect the incapacitated Cybermen's weapons for the next assault.

Ben has reached the bomb and begins the process of disarming it but, at the control centre, Cutler notices Barclay's absence. He goes to investigate, catches Ben while he is sabotaging the rocket and knocks him unconscious. Cutler suspects Barclay of being part of this mutiny but states he needs him for the launch of the rocket.

Later, Barclay starts the countdown to the launch of the Z-bomb. Ben regains consciousness but is disorientated and cannot remember if he sabotaged the rocket before being discovered by Cutler. The countdown approaches zero.

Episode 4
As the countdown to launch the Z-bomb reaches zero, the engines fail on the launch pad. Cutler is enraged. He threatens to kill Ben, Barclay and the Doctor, who has regained consciousness and returned to the tracking room. Driven mad with grief by the apparent death of his son in the Zeus V rescue capsule, Cutler is oblivious to the warnings that another force of Cybermen are attacking the base. He also ignores the Doctor's protestations that Mondas is on the verge of burning up.

As he is about to carry out his threat and kill the Doctor, Cutler is killed by the invading Cybermen. The Doctor tries to mediate with the Cybermen, offering them a home on Earth to replace their broken up planet. The Cybermen say they will not even think about negotiations with a missile pointed at their planet and demand that it be removed before they begin negotiations. As a makeweight, they take Polly as a prisoner onto their ship.

As soon as they arrive at their ship, the Cybermen render Polly unconscious and place her in a large metal chair.

The Doctor takes charge of the control centre and contacts the International Space Centre, who themselves have been taken over by Cybermen, to tell them of the situation. The Cyberman in Geneva contacts the Cyberman at Snowcap and informs him that they must move to their secondary objective, which the Doctor assumes to be the destruction of Earth. The Doctor goes on the loud speaker system and warns all of Snowcap of this.

Down in the pit of the Z-bomb, Ben, Barclay, Haines and Dyson are disarming the bomb. Ben raises the question as to why the Cybermen are not doing this themselves, what with them being naturally stronger. Ben hypothesises that they are intolerant to the radiation in the bomb. Dyson, Haines, Barclay and Ben put this to the test by playing dead and drawing in the Cyberman guard from outside, who immediately is rendered immobile. Ben uses this knowledge to order the return of Polly; however, the Cybermen refuse to relent. The Doctor is now taken to the Cybership. The Cybermen warn Ben that both he and Polly will be killed unless they give up the bomb. Ben looks around for something in the room that is portable and radioactive that they can use to their advantage. With the help of Barclay and Dyson, he uncouples something from the back of one of the computers he can use for this purpose. They hide behind the door as the Cybermen approach. The Cybermen attempt to gas the four men out. When Ben and the rest cannot take any more, they open the door and use a combination of the deactivated Cyberman's gun and the radioactive equipment to deactivate the Cybermen. However, Haines is killed.

On returning to the control base of Snowcap, Barclay shows Ben a device that the Cybermen used to contact each other. Ben uses it randomly to draw the Cybermen in. Whilst they wait, the lights dim as Mondas draws yet more power from Earth. As the Cybermen approach, one of the scientists points to the screen where they see Mondas flash brightly and melt. The Cybermen that were approaching the humans disintegrate as the power source they had drawn from has been retarded. Zeus V returns onscreen; its pilot explains that all power has been restored and he can attempt re-entry.

Ben runs out to the Cybership to free Polly and a semi-conscious Doctor. The Doctor seems to deliberate as to whether "it's all over" before settling that it's "far from being all over" and alerting his companions that he must return to the TARDIS immediately. Ben gives him his cloak so he won't "catch his death of cold", but the Doctor gives him an unusually distant reply, concerned with something more important at hand. He says, "Ah, yes. Thank you. It's good. Keep warm," in a very abbreviated way, without a lick of humour to be found. Bearing little attention to Ben or Polly, he even deserts them, rushing off alone.

The weary Doctor returns to the TARDIS and closes the door, trying to take care of a dire situation by himself — his body has worn too thin and he is dying from old age, but very soon, that problem will be resolved. He wants his companions safely away from him when a particular event happens, but they are protesting for him to let them inside anyway. As Ben and Polly hammer on the door, the controls operate of their own accord and the central column begins to rise and fall. The Doctor seizes enough energy to open the door, and Ben and Polly finally get in. Barely conscious, the Doctor collapses to the floor. Ben and Polly stand back as the Doctor becomes enveloped in a bright light. After the light dies down, the Doctor's face is different and has the appearance of a younger, dark-haired man...

Cast

 * Dr. Who - William Hartnell
 * Polly - Anneke Wills
 * Ben - Michael Craze
 * General Cutler - Robert Beatty
 * Williams - Earl Cameron
 * Dyson - Dudley Jones
 * Barclay - David Dodimead
 * Schultz - Alan White
 * Tito - Shane Shelton
 * American Sergeant - John Brandon
 * Wigner - Steve Plytas
 * Radar Technician - Christopher Matthews
 * Krail - Reg Whitehead
 * Talon - Harry Brooks
 * Shav - Gregg Palmer
 * Geneva Technician - Ellen Cullen
 * TV Announcer - Glenn Beck
 * Cyberman Voices - Roy Skelton, Peter Hawkins
 * R/T Technician - Christopher Dunham
 * Terry Cutler - Callen Angelo
 * Krang - Harry Brooks
 * Jarl - Reg Whitehead
 * Gern - Gregg Palmer

Uncredited cast

 * Dr. Who - Patrick Troughton
 * Haines - Freddie Eldrett
 * Soldier in Tracking Room - Ken McGarvie
 * Soldiers - Terence Jones, Roy Pearce, Freddie Eldrett, Nick Hilton, Peter Pocock
 * Second Engineer - Roy Pearce
 * Countdown voice - Roy Skelton
 * Snowcap voices - Roy Skelton, Glenn Beck
 * Double for Ben - Peter Pocock
 * Double for Dr. Who - Gordon Craig
 * Cybermen - Bruce Wells, John Knott, John Haines
 * Tracking room technicians - Richard Lawrence, Morris Quick, Bill Gosling, Gordon Lang
 * R/T technician - Nicholas Edwards
 * Corporal - Alec Coleman
 * Coloured High Ranking Officer - Chris Konyils
 * Geneva Secretary - Sheila Knight
 * Spanish High Ranking Officer - Stanley Davies (all DWM 214)

Crew

 * Assistant Floor Manager - Jenny McArthur
 * Costumes - Sandra Reid
 * Designer - Peter Kindred
 * Make-Up - Gillian James
 * Producer - Innes Lloyd
 * Production Assistant - Edwina Verner
 * Script Editor - Gerry Davis
 * Special Sounds - Brian Hodgson
 * Studio Lighting - Howard King
 * Studio Sound - Adrian Bishop-Laggett
 * Theme Arrangement - Delia Derbyshire
 * Title Music - Ron Grainer

Animation Unit
A Planet 55 Production for Pup Ltd
 * Inbetweeners
 * Yvonne Wilcox
 * Jenna Batcheldor
 * Konstara Prawiro
 * Heather Sillince
 * Morgan Tate
 * Additional Compositing and Colour Grading - Thaumatury
 * Compositor and Grader - David Devjak
 * Compositors
 * Conor Bowes
 * Sean Mundy
 * Chris P. Chapman
 * CGI Set Reconstructions - Aaron J. Climas
 * Junior Animators
 * Jake Opperman
 * Crystal Chappell
 * Avalon Eyres
 * Editor - Josh Campbell
 * Lead Animator Backgrounds - Paul Johnson
 * Lead Animators
 * Sean Zwan
 * Colin Bennett
 * Zhe Xiang Tang
 * Chris P. Chapman
 * Audio Restoration and Mastering - Mark Ayres
 * Thanks to
 * Graham Strong
 * David Holman
 * Assistant Producer - David Breen
 * Assistant Director - Sean Zwan
 * Producer - Stephanie Youlten
 * Director/Producer - Austen Atkinson
 * Executive Producer for Big Finish - Jason Haigh-Ellery
 * Executive Producer - Dan Hall

Biology

 * Space fatigue is hypothesised as the cause of the Zeus IV pilots' tiredness, influenced by Mondas' gravity.

Foods and beverages

 * Polly makes several cups of coffee.

Locations

 * Polly is amazed by the stock of clothes in the TARDIS' wardrobe and she jokingly wonders if the Doctor went shopping in Carnaby Street.
 * The observatories of Jodrell Bank and Mount Palomar are said to confirm the appearance of Mondas in the sky.
 * Terry Cutler leaves Earth from the Woomera cosmodrome.

Individuals

 * Ben calls Polly "Nanook of the North" because of her fur coat.
 * Philips is stationed at the base.

Media

 * International Television News is the television channel which announces the appearance of Mondas.

Organisations

 * Space flights are governed by a multinational body known as International Space Command.

Popular culture

 * Tito sings an excerpt of the song La donna è mobile.
 * When the Doctor announces a visitor, Ben jokes about being visited by Father Christmas.

Planets

 * An Earth expedition has just returned from the Moon.

Technology

 * A retinascope is part of the rocket.
 * Nuclear Z-Bombs, able to destroy a planet or turn it into a star, can be launched via a Demeter rocket.
 * According to Ben, locks are different than the 1966 ones, so he cannot force them.

Story notes

 * This is the first time the regeneration process is seen. The process is not given a name until Planet of the Spiders in 1974.
 * Only episodes one, two and three of this four-part story exist in the BBC Archives as 16mm black & white film telerecordings. Only short clips of footage from the missing episode four exist, among which are the regeneration sequence itself; the sequence exists thanks to it having been included in an early 1970s edition of Blue Peter that discussed the transition to the new Doctor. The regeneration is one of several sequences from lost episodes (Katarina's death in The Daleks' Master Plan being another) that were inadvertently preserved through their use on Blue Peter episodes that were not wiped.
 * William Hartnell left Doctor Who due to bad health, but upon leaving had said, "If there is one man in England who can replace me as the Doctor, it's Patrick Troughton!" Troughton took over the role of the Doctor when Hartnell regenerated into Troughton. Hartnell returned in The Three Doctors in 1972 to celebrate the show's tenth anniversary. He died three years later.
 * William Hartnell did not appear in episode three. On the Monday before the programme was due to be recorded, he sent a telegram to the production team informing them that he was too ill to work. Gerry Davis rewrote the script to explain the Doctor's absence (his sudden collapse) and gave his dialogue to other characters, most noticeably Ben. This was not as much of an interruption to the episode's production as it would seem, as all four episodes had been written so that Hartnell would have relatively little to do in case of just such an event. The original draft of episode four did not feature the Doctor regenerating at the end. This has led to the sad irony of the last surviving episode of William Hartnell's era not featuring William Hartnell.
 * Special "computer tape"-style opening and closing title graphics were created for this story by graphic designer Bernard Lodge.
 * This is the only TV story to give Cybermen characters individual names (Krang, Jarl etc). After this, Cybermen were only ever named by rank (Cyberleader, Cybercontroller etc).
 * This is the first time that the second broadcast story of a season did not feature the Daleks.
 * At the time of the serial's original broadcast, as well as the timeframe of the serial (1986), Pluto was still considered a planet and therefore the story title and dialogue referring to Mondas as the solar system's tenth planet was correct.
 * The First Doctor's last words were originally scripted as something similar to "No... no, I simply will not give in!" Time was running short towards the end of production, and Derek Martinus opted not to record the line, wanting to ensure that the regeneration sequence was recorded as well as possible. As a result, the First Doctor's last words were simply, "Ah! Yes. Thank you. That's good, keep warm." In Twice Upon a Time, the Doctor's final words are given as "well then, here we go, the long way round."
 * In the original script, the Cybermen had human faces (albeit all rather similar), with a metal plate under their hair. Their hands were also to be human, although their arms would be transparent, made up of rods and lights. A movable arm was also to extend from each Cyberman's chest unit, but such an accessory was considered too costly to implement.
 * Williams was originally Welsh. Derek Martinus cast Bermudan actor Earl Cameron in the role, deciding that he could be black and Welsh.
 * Michael Craze found this work difficult, as he had just undergone surgery to remove a bone chip from his nose (during which he suffered a burst blood vessel which nearly cost him his life) and the jabolite "snow" blown around the film stage irritated his nose badly. Nonetheless, Craze was undeterred from asking out production assistant Edwina Verner, whose job it was to throw the jabolite into the wind machine — and the two would subsequently marry.
 * The Doctor shows some understanding of the Cybermen, although the precise extent of his knowledge is not made clear. A few future stories in spin-off media use this as an opportunity to imply that he has met or heard of the Cybermen before:
 * In The Alchemists, Susan states in a letter intended for Barbara that gold, a weakness of the Cybermen established in Revenge of the Cybermen, is useful for fighting "certain things".
 * In Byzantium!, in which he is still travelling with Ian, Barbara and Vicki, the Doctor remembers a visit to Mondas.
 * In The Empire of Glass, the First Doctor chairs the Armageddon Convention which, although the Cybermen do not attend, outlawed the use of Cyber-bombs according to Revenge of the Cybermen.
 * In Salvation, Steven thinks of the Cybermen when thinking of evil beings, although this could also be from his pre-companion years as a fighter pilot.
 * The First Doctor and Susan do encounter the Cybermen in Prologue: The First Doctor, a teaser comic strip for Supremacy of the Cybermen. However, this event takes place in an alternate timeline of An Unearthly Child which is ultimately undone.
 * The Doctor and Susan encounter Cybermen in Dr. First, clearly stating that the Doctor had had numerous encounters with the species before the story.
 * The novelisation of Twice Upon a Time states that the Doctor knew of the history of the Cyberman invasion before the events of this story, so he deliberately acts as a passive observer while the historical events play out, although he stays ready to intervene if necessary.
 * The missing episode four, animated in 2013, begins a run of seven animated reconstructions through to the end of TV: The Power of the Daleks, which was released in animated form three years later. This was the longest consecutive run of animated reconstructions produced by the BBC until 2019 when it was announced that TV: The Faceless Ones would be receiving an animated reconstruction.
 * With the UHD Blu-ray release of TV: Twice Upon a Time in September 2018, The Tenth Planet has become the first and, to date, only classic-era serial to see footage upscaled to 4K resolution.
 * Episode four of this story begins a run of twelve missing episodes that concludes with episode one of The Underwater Menace. As of 2020, this is the longest run of missing episodes.
 * Anneke Wills recalled that the Cybermen had her in stitches because they looked so cheap, but the actors were all "six foot hunks".
 * Michael Craze initially didn't think much of the Cybermen, recalling that they were held together by sellotape.
 * The regeneration scene took a whole day to film.
 * Footage of a Blue Streak missile test was used for the launch of the Zeus IV spacecraft.

Ratings

 * Episode 1 - 5.5 million viewers
 * Episode 2 - 6.4 million viewers
 * Episode 3 - 7.6 million viewers
 * Episode 4 - 7.5 million viewers

Myths

 * An attempt was once made to colourise parts of this story. (This was an April Fools' joke in Doctor Who Magazine.)
 * A test regeneration was filmed during production of The Smugglers. (This too was an April Fools' joke in Doctor Who Magazine.)
 * The master copy of episode four was lost in 1973 after being lent to the BBC's children's magazine programme Blue Peter for a feature they were compiling about the series. (It is unknown how this episode came to be lost; the episode that was lost after being lent out to Blue Peter was "The Traitors", the fourth episode of The Daleks' Master Plan.)

Filming locations

 * Ealing Television Film Studios

Production errors

 * The writing credit for episode one has Kit Pedler as "Kitt Pedler" and title music is credited to "ByRon Grainer" (and due to all letters being capitalised it appears to be "Byron Grainer", as in the first name "Byron"), when it should read, "By Ron Grainer"; for episode three, Gerry Davis becomes "Gerry Davies".
 * Sometimes the Cybermen start to talk before their mouths open.
 * The Cyberman helmets were held together with Gaffatape, which can clearly be seen in this episode.
 * When the Cybermen are ambushed outside, one of them has part of his headpiece (one of the "jug handles") come loose.
 * On two occasions, Robert Beatty fluffs his lines, as a result of which Cutler mistakenly refers to Wigner as "General Secretary" instead of "Secretary-General".
 * The reprise at the start of episode three is a remount of episode two's cliffhanger, not a telerecording of the final moments of episode two, and the dialogue between Cutler and the technician at the beginning of episode three is slightly different from that which closed episode two.
 * In episode four, Michael Craze commits a . He accidentally says "plonet Mandos" instead of "planet Mondas."
 * In episode two, while Krail is proposing his plan to take the humans to Mondas (and after the Doctor has shouted his objections), his head-mounted lamp / "third eye" starts reflecting studio lights.
 * At the beginning of episode two, when the Cyberman looks past the camera, the wall showing the Antarctic behind him briefly cuts off, showing the studio.

Continuity

 * The specific design of the Cybermen featured in this story would be seen in many adventures.
 * Mondas' origins prior to this story are explored in AUDIO: Spare Parts.
 * The Eighth Doctor later encountered these rudimentary Cyberman variants in Vienna on 11 September 1873. (AUDIO: The Silver Turk)
 * The Twelfth Doctor and his companions later witnessed the inception of a version of these prototypical Cybermen, which he recognises on sight as a "Mondasian Cyberman", on a Mondasian colony ship that had been trapped in the grasp of a black hole. (TV: World Enough and Time) In this case, the Doctor would call the Genesis of the Cybermen as an example of parallel evolution occurring in many places in space and time. (TV: The Doctor Falls)
 * The Doctor claims his body is "wearing a bit thin". This phrase is echoed by his war incarnation before he regenerates. (TV: The Day of the Doctor)
 * The Cybermen would later attempt to gain access to time travel, hoping to destroy Earth in 1985, thus preventing the destruction of Mondas. However, their efforts were thwarted by the Sixth Doctor and Peri Brown. (TV: Attack of the Cybermen)
 * The Doctor would later return to Antarctica in the 1970s during his fourth incarnation (TV: The Seeds of Doom) and, during his seventh incarnation, in 2006, (PROSE: Iceberg) 2012 (AUDIO: Frozen Time) and 2045. (AUDIO: The Word Lord) The Twelfth Doctor would return to Antarctica at the same time as the First Doctor when he was also on the verge of regenerating. (TV: The Doctor Falls, Twice Upon a Time)
 * Twenty years after they helped the Doctor prevent the return of Mondas in their personal timelines, Ben and Polly — who had gone their separate ways in life following their return to Earth on 20 July 1966 — reunited on 31 December 1986, which was by then their present. Ben believed that numerous governments may have covered up the return of Mondas and the Cyberman invasion of the Snowcap. Even after twenty years, Ben still had nightmares about the Cyberman in the projector room. (PROSE: Mondas Passing)
 * In the aftermath of the attempted Cyberman invasion, Professor Allison Williams led the scientific team which examined their ship. (PROSE: The Power of the Daleks)
 * Unbeknownst to the Doctor, his regeneration into his second incarnation was witnessed by his deceased companion Oliver Harper, who was killed by the Vardans on Grace Alone but remained as a ghost in the TARDIS. (AUDIO: The First Wave)
 * Earth would again be threatened by the approach of a planet in 2009, in that case Gallifrey. (TV: The End of Time)
 * After departing Ben and Polly, the Doctor resisted his regeneration out of fear, ultimately meeting a future incarnation that was also resisting regeneration. Following an adventure with his future self, the Doctor returned to Antarctica where he was found by Ben and Polly before regenerating. (TV: The Doctor Falls, Twice Upon a Time)

Digital releases
Until 31 October 2017, this story was available in BBC Store (UK). The fourth episode was represented as an animated reconstruction with original soundtrack.

DVD, VHS and audio releases

 * This was released on VHS video in 2000 in a box set with Attack of the Cybermen, with a reconstruction of the missing episode four. A release was originally planned in 1993 with a cover commissioned and drawn by Andrew Skilleter, but this was cancelled.
 * Editing and reconstruction for release was completed by the Doctor Who Restoration Team.
 * The soundtrack to this story, with linking narration by Anneke Wills, was first released on 1 November 2004, as part of a metal box set titled Doctor Who: Cybermen. It was re-released as a single CD on 9 January 2006, and again as part of the box set Doctor Who: The Lost TV Episodes - Collection Three on 4 August 2011.
 * It was released on DVD for the first time in the Regeneration box set, a limited-edition set released in Region 2 on 24 June 2013 and in Region 4 on 4 September 2013. The fourth episode was animated. The animation was done by Planet 55.


 * The Tenth Planet was released on DVD in October 2013. The fourth episode was entirely animated.

Contents:
 * Audio commentary with Anneke Wills (Polly), Christopher Matthews (Radar Technician), Earl Cameron (Glyn Williams), Alan White (Dan Schultz), Donald Van Der Maaten (Cybermen Shav and Gern), Christopher Dunham (R/T Technician) and designer Peter Kindred. Moderated by Toby Hadoke.
 * Frozen Out - Making of The Tenth Planet
 * Episode 4 VHS Reconstruction
 * William Hartnell interview from 1966
 * Doctor Who stories - Anneke Wills
 * The Golden Age - Historian Donald Sandbrook examines the myth of a Golden Age of Doctor Who
 * Boys, Boys, Boys! with Peter Purves, Frazer Hines and Mark Strickson
 * Companion Piece - A Psychologist, writers and some of the Doctor's Companions (Nicola Bryant, Arthur Darvill, Elisabeth Sladen, Louise Jameson among others) examine what it means to be a Time Lord's fellow traveller
 * Blue Peter Tenth Anniversary retrospective on Doctor Who's history
 * PDF Materials
 * Photo Gallery