The Doctor is warned of the arrival on Earth of a terrible new threat. The murderous renegade Time Lord known as the Master has stolen a Nestene energy unit and established a base of operations at a plastics factory where he has placed the owner, Farrel, under his mental influence. When the Doctor's new assistant, Jo Grant, stumbles upon the Master, she too is hypnotised, with orders to trigger a lethal trap for the Doctor. But this is not the only snare the Master has prepared for the Doctor, even as he plots a new Nestene invasion of the Earth.

Barry Letts was appointed the producer of Doctor Who at very short notice, midway through the recording of its seventh season. As a result, his influence on that year's stories was minimal. The opportunity to really make his mark finally came in late February 1970, when he was informed that Doctor Who was to continue into an eighth season. This had been a source of uncertainty for some time; indeed, Letts had undertaken work on a potential replacement show about a displaced Australian cowboy called Snowy White. But with Doctor Who's future now assured, at least for the time being, Letts made four major decisions which would have a substantial impact on the series, both on-screen and off.

First, having secured a larger budget for Season Eight, Letts was able to split it into five stories -- one more than had comprised Season Seven. This meant that Letts could avoid the lengthy seven-part serials which had been predominant the year before; no story in the eighth season would be longer than six episodes. In this manner, Letts would be able to ensure that there would be more “first nights”, which he and Head of Serials Ronnie Marsh felt were important for the programme's ratings.

Two Doctor Who episodes would now be recorded together every fortnight

Second, Letts decided that the altered recording schedule with which he had experimented on both The Silurians and Inferno during Season Seven would now become the norm. Instead of taping one installment each week, two episodes would now be recorded together every fortnight, thereby reducing wear and tear on sets; for instance, a set which was needed throughout a six-part story would only have to be erected and taken down three times, rather than half a dozen.

Third, Letts and script editor Terrance Dicks decided that the Doctor should gain a new assistant through his attachment with the United Nations Intelligence Taskforce (UNIT). Letts felt that the previous companion, Liz Shaw, was too intelligent and independent to play second fiddle to the Doctor, and he wanted to soften the rather ascetic UNIT environment. Letts had enjoyed the dynamic of the Doctor being accompanied by both female and male characters, as had been the case when he directed The Enemy Of The World in 1967. As such, he and Dicks developed Josephine “Jo” Grant, whom they envisaged as being more charming but less science-oriented than Liz. Her male counterpart, with whom there would be the possibility of romantic involvement, would be UNIT Captain Mike Yates; Yates would also act as Brigadier Lethbridge-Stewart's second-in-command, rather than continuing the revolving door of UNIT captains seen during Season Seven.

Finally, Letts and Dicks agreed that Season Eight should feature a major gimmick to attract new viewers. With the exiled Doctor acting as a sort of modern-day Sherlock Holmes, they thought it would be appropriate to introduce an archnemesis in the vein of Holmes' foe, Professor Moriarty. This new villain, whom Letts and Dicks hoped would replace the Daleks at the forefront of Doctor Who's rogues gallery, would be a renegade Time Lord like the Doctor, but with an inclination towards evil. Drawing upon the academic implications of the Doctor's own moniker, Dicks christened this character “the Master”.

With the fundamentals of Season Eight now defined, the next priority for the production team was to secure their cast for the new year. To this end, Jon Pertwee was quickly contracted on March 9th. Letts had created the Master with Roger Delgado in mind, and he agreed to appear throughout Doctor Who's eighth season on March 23rd; Letts and Delgado had worked together on several occasions during the producer's acting days. Next to commit to Season Eight, on April 8th, was Nicholas Courtney, who played the Brigadier. Later, on June 22nd, John Levene agreed to appear in eighteen episodes as Sergeant Benton.

Asked to provide a return appearance for the Autons, Robert Holmes agreed only reluctantly

To write the new season's debut serial, Dicks recruited Robert Holmes. Holmes had most recently written the previous year's premiere adventure, Spearhead From Space, with which Dicks had been very pleased. In addition to introducing Jo, Mike and the Master, Holmes was asked to provide a return appearance for the Autons and their plastic-controlling masters, the Nestene Consciousness, which he had created for Spearhead From Space. Holmes agreed only reluctantly; he disliked recycling old monsters, preferring to devise original concepts for each serial. A storyline entitled “The Spray Of Death” was commissioned from Holmes on April 28th, followed by full scripts on June 12th.

As Holmes developed “The Spray Of Death”, several modifications were introduced. Keen to make Jo's role in the first episode more prominent, Dicks suggested the sequence where she discovered the Master operating out of Farrel's factory, and subsequently set off the booby-trapped box under the evil Time Lord's post-hypnotic suggestion. Originally, the bomb had simply gone off when the Doctor tried to open the box by remote control. The elder Farrel's immunity to hypnotism -- justifying the Master's decision to have him killed -- was Dicks' idea as well. The victim of the Master's murderous phone cord was originally the Brigadier, rather than the Doctor. Dicks also added dialogue explaining that Liz Shaw had returned to Cambridge, since the character had not been written out at the end of the previous season's finale, Inferno.

The troll dolls initially played a much greater role in the story's climax, justifying the Master's interest in the circus, which would have been used to distribute the toys. Dicks disliked Holmes' idea that the plastic daffodils (and, at one point, the troll dolls) would be animated when the temperature reached a certain level, with the Master anticipating a forthcoming heat wave in Britain. Dicks felt that this made the story's setting illogical -- it would make more sense for the Master to carry out his plan in a tropical locale -- and so the temperature trigger was replaced with a broadcast activation signal. The attempted arrival on Earth of a Nestene energy form was added to Episode Four at this point.

Towards the end of June, auditions began for the two new UNIT regulars. About fifty actresses were interviewed for the role of Jo Grant. Letts and Dicks had already shortlisted three performers -- all of whom wanted to play Jo in the vein of the female protagonists of The Avengers -- before they met with one of the final candidates, Katy Manning. Manning was late to the audition after going to the wrong building and, having forgotten the glasses she needed to compensate for her extreme near-sightedness, she was unable to read her script. Nonetheless, Letts and Dicks were charmed by Manning's improvised, scatterbrained audition and, after a callback the next day, she was offered the part. Pertwee concurred with the casting decision: he had met Manning at the BBC some months earlier, at which time he had sensed that she was well-suited to Doctor Who.

Barry Letts' first choice to play Mike Yates was Ian Marter

Meanwhile, Letts' first choice to play Mike Yates was Ian Marter. However, it soon became clear that preexisting commitments meant that Marter would not be available for the entirety of Season Eight, and so he had to drop out of consideration; four years later, he would instead be cast as companion Harry Sullivan. Letts next turned to his second choice, Richard Franklin, whom he had recently seen in a West End play. Franklin was contracted for all five serials on July 1st while, two days later, Manning committed to a minimum of twenty episodes.

Letts decided to direct “The Spray Of Death” himself, and had negotiated permission to do so when he became Doctor Who's producer. For the new season, costume designer Ken Trew was eager to make the Doctor more colourful, after the character had spent Season Seven largely being dressed in monochrome. As such, Pertwee would henceforth be given more brightly-coloured smoking jackets and capes to wear. For the Master, Trew designed a black costume with a high collar, styled in the manner of Pandit Nehru, the first Prime Minister of India. Ironically, this had been a look which Pertwee had originally suggested for the Doctor.

Franklin joined the cast for the start of location work on September 17th, which saw cast and crew visiting several venues, most of them in Buckinghamshire. In Chalfont St Peter, the Daffodil Man Autons handed out plastic flowers at the St Peter's Court shopping centre and the Church Lane parking lot. Next, various roadside sequences were filmed at Hodgemoor Woods near Chalfont St Giles. The day concluded back in London, with the booby-trapped box exploding at Queen's Wharf in Hammersmith. Manning and Delgado's first day on Doctor Who was September 18th, which was spent at the Roberts Brothers Circus. Erected in Leyton, London, it doubled for the Rossini Brothers fairground.

Production resumed after the weekend on the 21st, when the scenes of the Doctor and Jo being pursued by Autons were filmed in a quarry owned by the Totternhoe Lime and Stone Company near Dunstable, Bedfordshire; this material had originally been written for a woodland environment. During this work, Manning -- who was unable to wear her glasses as Jo -- badly twisted her ankle. Manning was already nervous about being the junior member of the regular cast but now, provoked by jokes made by production assistant Nicholas John -- the brother of Caroline John, who had played Liz Shaw -- she became anxious that she might be fired. Pertwee came to his co-star's defence, rebuking John for his comments. In fact, Pertwee himself would later voice concerns about Manning's severe myopia to Terrance Dicks, although the two actors would quickly form a close and enduring bond. Manning was taken to hospital to have her ankle examined, but returned to work shortly thereafter.

Also injured the same day was stuntman Terry Walsh, who was playing one of the Auton policemen. After being hit by the UNIT jeep, he fell further down the escarpment than planned, although he was able to finish the shot. Furthermore, Nicholas Courtney arrived at the quarry in ill health following an attack of depression the night before. Courtney's condition was noted by both Pertwee and Letts, and he was excused from most of the day's filming so that he could seek medical intervention.

Courtney remained absent on September 22nd, which saw the start of filming on the Beacon Hill material at the GPO Relay Station tower in Caddington, Bedfordshire. A double stood in for Courtney, and most of the Brigadier's dialogue was deleted or reassigned. Letts inserted the element of Jo twisting her ankle, to explain the limp from which Manning now suffered. Another last-minute change was to have the faux Master shot at the story's conclusion revealed to be a hypnotised Farrel; as scripted, the decoy was actually an Auton. A model shot of the research establishment was also captured.

The Beacon Hill sequences were completed on September 23rd, after which location work concluded back in Dunstable, where Thermo Plastics Ltd posed as Farrel's factory. Courtney rejoined the team, although Letts agreed to reduce the amount of dialogue he would be given, to make the work less stressful. On the 24th, Manning was introduced to the press as the Doctor's newest companion. At around the same time, it was decided to amend the serial's title to Terror Of The Autons, since the plot element of the plastic flowers was not introduced until Episode Three.

Following Letts' new production schedule, Terror Of The Autons was recorded fortnightly on Fridays and Saturdays, with the first block taking place on October 9th and 10th at BBC Television Centre Studio 8 in White City, London. Unusually, Letts decided to reserve the first day for special effects sequences, notably those involving Goodge's miniaturised corpse, as well as the troll doll in the elder Farrel's car and living room. As he had done to a much more limited extent during Season Seven, Letts was eager to experiment with the new chroma key technology now available to colour television. The second day saw the recording of most of Episodes One and Two.

Originally, the Doctor vowed that the Master would stay on Earth “until I destroy him. Or until he destroys me.”

During rehearsals for the second studio block, the scripts underwent two notable amendments. First, Dicks realised that the story's new title meant that an Auton needed to appear somewhere in Episode One, and so he added the scene where one was animated by the Master. Meanwhile, Ronnie Marsh had objected to the Doctor's vow in Episode Four that the Master would stay on Earth “until I destroy him. Or until he destroys me.” Instead, the Doctor now suggested that he was looking forward to their next contretemps. Meanwhile, Haydn Jones, who had been cast as the telephone repairman -- really the Master in disguise -- had been given a more prominent role in the next serial, The Mind Of Evil. As such, Norman Stanley was hired at short notice to replace Jones in Terror Of The Autons. The second recording block occurred on October 23rd and 24th, this time in TC6. Again, the Friday was used for shots requiring extensive use of chroma key and other special effects, while the Saturday saw the completion of Episodes Three and Four.

Season Seven had already witnessed a significant increase in the amount of editing performed on Doctor Who episodes but, with Season Eight, new facilities became available which would provide directors with an even greater ability to tailor each installment to their liking. On Terror Of The Autons, Letts chose to delete an entire sequence from Episode Three in which an unsuspecting policeman stumbled upon the Auton coach and was murdered after discovering that the Daffodil Men were not human. Bill McGuirk, who played the unfortunate constable, was still listed in the credits, despite all of his material winding up on the cutting room floor. Also excised was a comment by the Time Lord in Episode One, who explained that the Master had been helped to escape imprisonment.

The first part of Terror Of The Autons inaugurated Doctor Who's eighth season on January 2nd, 1971. During the twenty-seven weeks which had elapsed since the last part of Inferno, the timeslot had largely been filled by The Best Of Basil Brush during the summer, and then The Pink Panther throughout the autumn. For its new run, Doctor Who led into a news update and then the Lucille Ball sitcom Here's Lucy, which had also followed it during the first few months of 1969.

• Doctor Who Magazine #311, 12th December 2001, “Archive: Terror Of The Autons” by Andrew Pixley, Panini Publishing Ltd.
• Doctor Who Magazine Special Edition #2, 5th September 2002, “Something Old, Something New” by Andrew Pixley, Panini Publishing Ltd.
• Doctor Who: The Complete History #16, 2018, “Story 55: Terror Of The Autons”, edited by John Ainsworth, Hachette Partworks Ltd.
• Doctor Who: The Handbook: The Third Doctor by David J Howe and Stephen James Walker (1996), Virgin Publishing.
• Doctor Who: The Seventies by David J Howe, Mark Stammers and Stephen James Walker (1994), Virgin Publishing.