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The Android Invasion was the fourth serial of season 13 of Doctor Who. The final regular UNIT-based story, it saw the final appearances of John Benton and Harry Sullivan in the classic series.


The Fourth Doctor and Sarah find themselves in the English village of Devesham near a Space Defence Station. The village seems deserted, the telephones don't work, calendars are stuck on the same date and white-suited figures are wandering about aimlessly. Who are the Kraals and what are their plans for Earth?


Part one[]

A UNIT soldier walks, as if in a trance, through the woods, his right arm twitching spasmodically. Nearby, the TARDIS materialises. The Doctor and Sarah step out. The Doctor explains that the coordinates were set for Sarah's time, but the linear coordinates were off. They could be miles from London. In any case, Sarah is glad to be back on Earth. The Doctor detects an odd reading of energy or radiation nearby.

The Doctor and Sarah meet four figures in white overalls and helmets with dark-tinted visors. When the Doctor asks them for directions, they shoot at the travellers with their index fingers. The Doctor and Sarah duck and run, with the four in pursuit. The two manage to lose them but Sarah slips down a hillside and clings to a cliff ledge. The Doctor helps her up. They see the soldier, jerkily making his way towards the cliff's edge. The Doctor shouts at him to stop, but he pays no heed. He runs over the cliff and falls to his death.

Androids Attack AE 1

Androids attack the Doctor and Sarah.

The Doctor searches the body. He finds a wallet full of shiny, freshly minted coins, all dated the same year. They also spot a casket-shaped pod nearby, which the Doctor finds familiar. Before he can identify it, shots ring out. The white-suited figures have found them again. The Doctor and Sarah run again, avoiding their pursuers. They reach a village which Sarah recognises as Devesham. It lies about a mile from a Space Defence Station.

The village, however, is deathly quiet and seems empty. The Doctor decides to try the local pub, the Fleur-de-Lys, but it too is empty, and the Doctor finds the same freshly minted coins in the register. Sarah spots the white-overalled figures coming down the street, accompanied by the "dead" soldier. A large tradesman's pickup truck arrives, carrying on benches in the back what seem to be villagers, all in trances. Two of the white-overalled figures emerge from the truck's cab and help the villagers off; the villagers then distribute themselves around the village. Mr Morgan, the landlord of the pub, enters it with several other people while Sarah and the Doctor hide in the store room. The villagers take their seats silently, waiting motionless until the clock strikes eight, whereupon they suddenly come to life, acting normally.

The Doctor intends to get to the Space Defence Station and contact UNIT. He leaves, telling Sarah to meet him at the TARDIS if anything goes wrong. However, the "dead" soldier finds her in the store room and questions her. Morgan suggests that Sarah might be part of "the test". When Sarah asks what test, he tells Sarah that she should go.

Outside, Sarah hides behind the truck. She observes one of the white-overalled figures standing near the vehicle turn around. Its helmet visor is raised, but beneath is nothing but plastic and electronics. Sarah runs for the woods, reaching the TARDIS. She spots a similar pod next to the time machine and goes to examine it, leaving the TARDIS key in the lock. Suddenly, the TARDIS dematerialises. As Sarah is still trying to understand why, a hand reaches out from the pod. Startled, Sarah sees a man lying inside. When she goes closer and asks the man if she can help him, he grabs her by the throat. Sarah breaks free and runs.

At the Defence Station, the Doctor asks a soldier where the commanding officer is. The soldier just stares ahead, unresponsive. Also inside the building, Senior Defence Astronaut Guy Crayford is addressed by a disembodied voice. The voice, named Styggron, tells him there is a random "unit" within the complex and orders him to check it out.

The Doctor enters an office marked as being that of Brigadier Lethbridge-Stewart. It is empty. Crayford enters and points a gun at him. The Doctor introduces himself as UNIT's scientific advisor. Crayford has heard of him, but as the Brigadier is in Geneva, and Colonel Faraday is in command, there is no-one to confirm the Doctor's identity; he could be an impostor. Before Crayford can have the Doctor taken to detention, the Doctor flips the desk over and runs. He makes it outside before he is recaptured by the white-overalled figures. Sarah sees this and sneaks into the building. She goes to the Doctor's cell and unlocks the door to let him out. Behind them, a communicator on a wall swings back to reveal a stony alien face observing them.

Part two[]

Styggron contacts Crayford again, complaining about a second random unit. Crayford identifies these random units as the Doctor and Sarah. The alarm sounds, indicating the Doctor's escape. Crayford sends his UNIT soldiers to stop them. Hiding in a storage cupboard, the Doctor tells Sarah about Crayford. She says it is impossible. Crayford was in deep space testing the XK-5 space freighter when it vanished, presumed to be destroyed. The Doctor and Sarah venture out to find RSM Benton standing in the reception area. He points a pistol at them. Styggron wants the Doctor captured alive. When Crayford cancels the kill order, Benton seems to be dizzy, giving the Doctor and Sarah a chance to run away. Crayford orders Harry Sullivan to cordon off the perimeter road.

The Doctor and Sarah decide to return to the village and warn London. They are pursued by tracker dogs. Sarah twists her ankle in the woods, and this slows her down. The Doctor hides her in a tree, taking her scarf to draw the dogs away. He hides by submerging himself in a pond and the dogs lose his trail. Unfortunately, when the soldiers turn back, they spot Sarah and capture her. Styggron tells Crayford to locate, but not seize, the Doctor. He has other plans for him.

Styggron Reflected AE 2

Styggron examines a groggy "patient".

Meanwhile, in an alien-looking room, Sarah is strapped to a table. Harry tells her it is no use to struggle. Under Styggron's order, he starts the scan. In the village, the Doctor finds the telephones are not working. He meets Morgan, who tells him the lines are down after a gale. Styggron speaks to another of his kind, Chedaki, who feels the time for experiments are over. Styggron insists that they must confirm their techniques as flawless if they are to conquer worlds other than Earth. Styggron contacts Crayford and tells him to commence the final test.

In the pub, the Doctor finds more oddities: an unused dart board, plastic horse brass on the wall and a tear-off calendar with only one date: Friday, July 6. The telephone rings, and Morgan answers it. The call is for the Doctor. It is Sarah, who tells him she was captured but escaped. She asks the Doctor to meet her by the village shop and to be careful of the robots. He hangs up and finds that the telephone has stopped working again. The Doctor meets Sarah, who explains how she escaped. The Doctor remarks on the providence of her finding the only telephone in the village that worked. He believes they are being tested to find out how smart they are.

He decides to take Sarah to the TARDIS and use the radio there. However, the TARDIS is gone. The Doctor is puzzled: the ship is not programmed to auto-operate, unless... He asks Sarah for her TARDIS key. When she claims she has lost it, the Doctor tells her she never had it. When Sarah put the key in the lock and left it there, she cancelled the TARDIS's pause control, and it continued its journey to Earth. This is not Earth, this is not a real forest, and she is not the real Sarah. The imposter responds by drawing a pistol on The Doctor, who explains that he knew immediately that it was not the genuine article; the real Sarah wasn't wearing her scarf, which he pulls out of his coat pocket. Knocking the pistol out of the imposter's hand, he grabs it by the shoulders and demands to know where the real Sarah is. The imposter pulls free but falls to the ground, its face popping open to reveal the electronics underneath.

Part three[]

The android Sarah rises to its feet and fires its pistol at the Doctor's retreating form. Chedaki tells Styggron it was a foolish experiment. The Doctor could undo their plans. Styggron dismisses this. The village and the Doctor will be destroyed by a matter-dissolving bomb. The real Sarah is being kept alive so Styggron can test the virus he intends to use to cleanse the Earth of human life. All the while, Sarah is feigning unconsciousness and listening. When the coast is clear, she gets up and sneaks away.

The Doctor watches the truck drive into the village and evacuate the androids to the Kraal base. The Doctor is grabbed from behind by Styggron, who gets two of the white-overalled figures to tie him up while the Kraal places the bomb at the Doctor's feet. Luckily, Sarah has made it back to the village. She uses the Doctor's sonic screwdriver to cut his bonds. They run into the base and shut the door as the village dissolves into a wasteland.

Devesham Disappears AE 3

The duplicate Devesham disappears.

However, the two are surrounded by androids, who escort them to a cell. The Doctor tells Sarah that he should have realised — the radiation levels he picked up when they landed were those of Oseidon, the Kraal planet. The levels are increasing, and the planet will soon be uninhabitable. This is why the Kraals are invading Earth. The duplicated village and their androids are a training ground.

Crayford enters the cell and tells the Doctor that it is all for the best. Soon, the Kraals will send his ship back by space-time warp so he can make a normal landing. He has recently established radio contact with Earth. He fed them a story of how his ship was trapped in an orbit around Jupiter and he survived by rationing his supplies and recycling his water. With the world's attention focused on his landing, the space shells containing the androids will be taken for meteorites. The androids will emerge and pave the way for the main invasion fleet. He is helping the Kraals because, while Earth left him for dead, the Kraals rescued his ship and rebuilt his body. The Kraals only want to survive and have also promised him no humans will be harmed as long as they obey.

Styggron gets "Harry" to place a drop of the virus in a jug of water to be taken to the cell. Meanwhile, although the sonic screwdriver is useless on the door, the Doctor has removed a floor plate. He intends to use the wiring below to electrocute their android guard. "Harry" enters with the water and to take the Doctor away. Before the Doctor goes, he tells Sarah not to waste the water.

The Doctor is strapped to the Kraal analysis table. It will copy all his knowledge and experience. Despite what Styggron has told Crayford, he reveals he does intend genocide. Earth's resources are too limited to be wasted on an "inferior species". The virus, distributed by androids, will wipe the Earth clean in three weeks, then burn itself out. Styggron will signal the invasion fleet. Styggron leaves the machine to do its work. When it finishes, the stimulation will make the Doctor's skull burst.

Sarah rigs the wiring beneath the cell floor and sets a small fire to lure the android guard. He steps in the puddle of water and is electrocuted when Sarah applies the power cable. She makes her way to the Doctor and turns off the scan. She helps the disorientated Time Lord out of the base, heading for Crayford's rocket before it takes off. The rocket is launched, and the G-forces start to crush them.

Part four[]

Sarah blacks out but is awakened by the Doctor. He tells her that was nothing; there is a more dangerous ride ahead. Before the rocket lands, the pods will be ejected. The Doctor and Sarah will ride two of them to Earth to warn the real Defence Station. He cannot guarantee they will survive the trip. As they talk, neither notices a nearby pod open to reveal an android Doctor.

On Earth, Matthews at the Defence Station's scanner room picks up Crayford's rocket. Grierson, the man in charge, informs Colonel Faraday. Meanwhile, having found the TARDIS in the woods near Devesham, Benton and Harry have been searching for the Doctor and Sarah, to no avail. Benton is worried. He has never known the Doctor to leave the TARDIS key in its lock.

Faraday welcomes Crayford home on the radio, but the signal is broken up by the "meteor shower" of pods. Unusually, they slow as they enter the atmosphere. Some of the pods land in a nearby field. One opens up to reveal the Doctor. However, he is unable to find Sarah. Sarah, having landed elsewhere, finds the TARDIS in the woods. As she looks around, the Doctor taps her on the shoulder. However, this Doctor is an android. Behind it, a pod opens to disgorge another Sarah replica. The real Sarah runs for it. The XK-5 re-establishes contact and comes in for a landing. Harry and Faraday head for the rocket, not knowing that Styggron is there with Crayford.

The real Doctor enters the station and recognises the "dead" soldier. The Doctor shows him a pass and tells him that if he sees the Doctor again today, he is to report it to him immediately. The Doctor goes to the scanner room, leaving the soldier puzzled. When Benton tells him where Harry and Faraday are, the Doctor contacts them on the radio and urges them not to enter the rocket. He will meet them at the lift.

Four and SJS AE 4

The Doctor and Sarah hide from their android duplicates.

While the Doctor gives Grierson instructions for modifying the radar dish, an android Matthews has incapacitated Benton and introduced an android replacement. Grierson says that if the Doctor points the dishes down here, it will jam every piece of electronic equipment for miles. Faraday returns to the scanner room, demanding an explanation. The Doctor tells them about the Kraal invasion. However, he is too late: Harry and Faraday have been replaced, and the android Doctor is pointing a gun at him. He slams the door in the android's face and leaps through a window. Outside, he meets Sarah. The Doctor tells Sarah their only chance is to stop the androids before they take over the complex. He runs back towards the scanner room, bluffing his way past "Benton" by posing as his duplicate. Sarah climbs up the rocket towards the real Harry and Styggron.

Grierson finishes his modifications but is shot in the shoulder by the android Doctor before he can turn on the power. The android is about to shoot the original when Crayford enters, saying Styggron promised no killing. The "Doctor" calls him a fool and tells him about the virus. Crayford cannot believe this, but the real Doctor tells him that his rocket was actually hijacked by the Kraals. They did not reconstruct him, they brainwashed him. Realising the truth, Crayford rushes out, distracting the android long enough for the Doctor to make his move. In the struggle, the Doctor activates the radar, jamming all the androids in mid-step.

In the rocket, Sarah unties Harry and Faraday. Styggron enters, holding a ray gun on them, but Crayford appears and attacks him. The two grapple, and Styggron shoots Crayford. The Doctor makes his own entrance, punching the Kraal, who falls on the vial of virus, cracking it open. Styggron shoots the Doctor before he dies. Sarah is horrified, but the real Doctor shows up — he had programmed his duplicate to distract Styggron. The android disintegrates into its component parts.

Sarah and the Doctor make their way back to the TARDIS. Sarah says she is going to take a taxi home, but when the Doctor offers to take her home instead, she smiles, "How can I refuse?" They enter the ship, and it vanishes.


Uncredited cast[]


Uncredited crew[]


Foods and beverages[]



Story notes[]

  • This story had working titles of: The Kraals, The Kraal Invasion and The Enemy Within. A rumoured working title was Return to Sukkannan (also sometimes referred to as Return to Suknan[1] — correct spelling uncertain), but this was actually the title of a second storyline by Terry Nation which had been submitted to the Doctor Who production office at the same time but was apparently abandoned.
  • The story was influenced by the film Invasion of the Body Snatchers[2] and was the last Terry Nation script for Doctor Who for four years until his final script for the series, Destiny of the Daleks (1979). This was the first non-Dalek story scripted by Nation since 1964's The Keys of Marinus and was his only other foray away from his most famous creations.
  • This story marks the last appearances of John Levene (Sergeant Benton) and Ian Marter (Harry Sullivan) in the series. Both actors have told Doctor Who Magazine (#230 and #93 respectively) that they didn't enjoy the story: Levene, because Nicholas Courtney wasn't there; and Marter, because "There was no real reason for Harry to be in it... [he] couldn't see the point." The characters were mentioned (but did not appear) in Mawdryn Undead (1983), when Harry was said to be working with NATO and doing something "very hush-hush at Porton Down", while Benton was said to have left the army and become a second-hand car salesman. Unfortunately the last we see of Levene as the real Benton in The Android Invasion he was lying unconscious. Levene later reprised the role of Benton for the non-BBC independent video production, Wartime. However, in Marter's case, The Android Invasion was his final outing as Harry Sullivan — he dealt with diabetes later in life and passed away after suffering a heart attack on his 42nd birthday, 28 October 1986.
  • UNIT played a significant role in one more story, The Seeds of Doom, and thereafter vanished (save for a cameo in The Five Doctors) until 1989's Battlefield.
  • Barry Letts and Nicholas Courtney have both said in Doctor Who Magazine (#270 and #228 respectively) that the Brigadier was originally meant to be in the story. As Courtney had committed himself to a theatre tour, believing his Doctor Who days to be well and truly over, his part had to be replaced with Faraday (who was originally a Brigadier before being demoted to colonel). Courtney's other reason for turning the part down was because he'd been asked back for another story and then had his part cancelled at the last minute, having passed up other work, "and I was very annoyed". (DWM #228)
  • This was the first story to feature the return of a former companion, namely Harry Sullivan (Benton is not generally considered a companion). Harry also featured in montage sequences in Logopolis and Resurrection of the Daleks. Dialogue references to him would also be made in Mawdryn Undead and the The Sarah Jane Adventures episode Invasion of the Bane, with the latter also featuring a photograph of the character. In future years, the return of past companions would be a featured part of specials such as The Five Doctors and The Two Doctors, and also be incorporated into several storylines of the 2005-present revival.
  • Ian Marter continued his acting career and wrote several Doctor Who novelisations, an original novel featuring Harry called Harry Sullivan's War; and an unproduced screenplay with Tom Baker, Doctor Who Meets Scratchman.
  • Kenneth Williams noted this story in his diaries, writing that Doctor Who was getting "more and more silly".
  • This marks the first appearance of the Fourth Doctor's seldom-seen light grey tweed coat.
  • Elisabeth Sladen is credited as "Sarah" in Radio Times for part one.
  • Although credited for part one, Dave Carter (Grierson) does not actually appear; his scenes having been edited out before transmission.
  • Roy Skelton (Chedaki) is credited on-screen for part two, but is uncredited in Radio Times.
  • The Kraals were not featured in another Doctor Who story in any medium until the audio story The Oseidon Adventure in 2012.
  • The story Sarah went to Devesham to cover is referenced as a newspaper headline on the Sarah Jane Adventures BBC website.
  • This is the first appearance of UNIT without Nicholas Courtney as the Brigadier.
  • Former producer Barry Letts returns as a director for this story.
  • Originally, a key plot element was that the Kraal androids were in fact mirror images of the people they were imitating, and this was how the Doctor deduced that “Sarah Jane” was actually a robot. It was eventually decided that this would be too technically demanding to realise, and the action was suitably amended. The "mirror image" concept was reinstated for Terrance Dicks's novelisation of the story.
  • Terry Nation envisaged the Kraals as somewhat insectoid in appearance, although this idea was not used in the design work.
  • Ian Marter said he would have preferred it if Harry had died saving Sarah.
  • Tom Baker and Elisabeth Sladen notoriously rewrote and ad-libbed most of their material due to hating the script, including the entire ending scene.
  • Tom Baker actually submerged himself in the pond rather than have Terry Walsh double for him, despite having a phobia of water. Unfortunately, Baker inadvertently swallowed some of the stagnant water and had to be taken to the local hospital to have his stomach pumped — and he was suffering from a sore throat at the time. (This explains why Baker's voice sounds husky in some of the location scenes.)
  • Philip Hinchcliffe later admitted that the demise of UNIT was handled badly. He was also unimpressed by the delivery of the Kraals' lines behind the masks.
  • Terry Nation felt the story was a nice idea with an intriguing mystery, but didn't feel the end product quite fulfilled his vision.
  • The first scene of main guest lead Guy Crayford was removed in post-production, and was also the first scene featuring Grierson. Dave Carter is still credited for part one despite his only scene being cut.
  • Corporal Adams was originally a private and the script reveals his first name as Tom.
  • Barry Letts liked the script, made it look pretty and was pleased that Terry Nation had come up with something different. He also liked the Kraals and wondered why they never made a reappearance.
  • Time constraints meant that a scene in part four which would have explained how the Doctor reactivated his android duplicate, as well as accounting for the fate of the Kraal invasion armada, was cut.
  • When writing the scene where the Doctor is held captive in the centre of the village, Terry Nation had been uncertain what kind of structure would be available to which the Doctor could be secured. He had assumed it would be smaller than the memorial cross ultimately used and so, in the script, Sarah rescued the Doctor simply by slipping the bindings over the top of the structure. The use of the sonic screwdriver was a late amendment to address the practicalities of the scene as filmed.
  • Terry Nation drew on his that the Soviet Union had constructed detailed replicas of Western towns in remote areas, as training grounds for sleeper agents.
  • The calendar in the pub gives the date as Friday 6 July. In 1975, 6 July was actually a Sunday, and the nearest year where that date fell on a Friday was 1973; while the next suitable years would be 1979, 1984 and 1990.


  • Part one - 11.9 million viewers
  • Part two - 11.3 million viewers
  • Part three - 12.1 million viewers
  • Part four - 11.4 million viewers


  • This story was originally written to feature the Daleks rather than the Kraals. (It wasn't.)

Filming locations[]

  • National Radiological Protection Board (now known as Radiation Protection Division), Didcot, Oxfordshire
  • Tubney Wood, Tubney, Oxfordshire (location where the TARDIS materialises)
  • Worsham Quarry, Witney, Oxfordshire (location where Kraal capsules arrive on Earth)
  • East Hagbourne, Oxfordshire
  • Location filming for the Kraal-replicated village of Devesham took place in East Hagbourne, Oxfordshire, a few miles from Didcot.
  • BBC Television Centre (TC3, TC8), Shepherd's Bush, London

Production errors[]

If you'd like to talk about narrative problems with this story — like plot holes and things that seem to contradict other stories — please go to this episode's discontinuity discussion.
  • Bad editing makes it clear that Sarah's fall and roll in part one are not the same take as her hanging of the cliff.
  • Also, bad editing makes it clear that the UNIT soldier does not jump off the cliff.
  • Some of the things said in part one are out of sync.
  • When the rocket is in view, the differences between model shots and archive footage are obvious.
  • A gap between the bolt and the door jamb is visible after the service mechanics slide the bottom bolt of the cell door imprisoning the Doctor.
  • Wires are visible on the darts that are in the bullseye of the dartboard in the pub.
  • When Benton is supposedly knocked unconscious in part four, his eyes still flicker.
  • Towards the end of part four, the android Doctor's uppercut clearly makes no contact with Styggron.


Home video and audio releases[]

DVD releases[]

The Android Invasion was released on DVD on 9 January 2012 in the U.N.I.T Files Boxset with Invasion of the Dinosaurs.

Special Features[]

Video releases[]

This story was released on VHS in the United Kingdom and Australia in 1995 and the US in 1996.

External links[]


  1. The Android Invasion, A Brief History of Time (Travel)
  2. The Android Invasion. Doctor Who Classic Episode Guide. Retrieved on 1 December 2018.