When the TARDIS lands near the Detsen monastery in Tibet, the Doctor sets out to return a sacred ghanta, which he took with him for safekeeping centuries earlier. But when he arrives at Detsen, he is accused of murder by Travers, a British explorer who has been searching for the mythical Yeti, and whose companion has been savagely killed. The monks know of the Yeti, and believe that the Doctor is responsible for the violent tendencies they have recently displayed. Jamie and Victoria discover evidence that the Yeti are actually robots, convincing the Doctor that he must uncover the Intelligence controlling their actions.

Mervyn Haisman and Henry Lincoln were actors who had met while appearing in a 1963 episode of No Hiding Place. Both men were developing second careers as writers for television, and subsequently decided to collaborate. Lincoln was a friend of Patrick Troughton's, with whom he had acted on several occasions. When they met by chance one day, Troughton discussed his experiences playing the Second Doctor, and bemoaned the lack of Earth-based adventures in which he had participated to date. Lincoln related this encounter to Haisman, and they decided to develop a story based on modern myths which they could submit to the Doctor Who production office.

After considering the Loch Ness Monster, Haisman suggested making use of the Yeti, creatures which were purported to live in the upper reaches of the Himalayan mountains. The legend of the Yeti initially reached western Europe in 1887. it entered into popular culture during the first half of the twentieth century, at which time a misunderstanding gave rise to the synonymous term “abominable snowman”. Doctor Who producer Innes Lloyd saw merit in the storyline, and so Haisman and Lincoln were commissioned to write The Abominable Snowmen on May 2nd, 1967.

Keen to capture the Tibetan culture accurately, Mervyn Haisman and Henry Lincoln used authentic names and details

This was the first serial instigated by new story editor Peter Bryant, shortly after taking over from Gerry Davis. When Bryant was given a three-month test period as producer over the summer, his replacement, Victor Pemberton, also carried out some work on the scripts. Keen to capture the Tibetan culture accurately, Haisman and Lincoln used authentic names and details. Padmasambhava was an eighth-century Buddhist master who was invited to Tibet by its king, Trisong Detsen; “Khrisong” was an alternative transliteration of “Trisong”. Songsten (originally the more authentic “Songtsen”) and Ralpachan were named for other Tibetan monarchs. Yeshe Rinchen was a Tibetan imperial preceptor, while Sapan was another name for the Buddhist scholar Sakya Pandita; both hailed from the thirteenth century. Thonmi Sambhota was a seventh-century figure, traditionally held to be the creator of the Tibetan script.

Lloyd -- who returned to the job of producer following Bryant's trial run -- saw The Abominable Snowmen as a great opportunity to introduce more location work into Doctor Who. Consequently, many of the sequences which Haisman and Lincoln had envisioned as being recorded in the studio would in fact be designated for location filming. This helped determine which of The Abominable Snowmen and Brian Hayles' The Ice Warriors would be the first serial made as part of Doctor Who's fifth production block. (The Tomb Of The Cybermen, made at the end of the fourth block, was being held over to start the new season.) By July 22nd, Haisman and Lincoln's adventure had gotten the nod, at least in part because the substantial location work would be more easily accomplished during the summer.

On July 28th, the services of the Doctor's companions were secured for The Abominable Snowmen when both Frazer Hines and Deborah Watling were issued new contracts; Hines' also covered The Ice Warriors. Subsequently, Watling suggested to Lloyd that her father, veteran actor Jack Watling, might be suitable to play Travers. This jibed with Lloyd's own thoughts on the part, and the senior Watling was duly cast. Jack Watling had starred in television series such as The Power Game and The Plane Makers, and had appeared in feature films like 1958's critically-acclaimed Titanic drama A Night To Remember. Cast as Thonmi was David Spenser, whose partner was Victor Pemberton.

The director assigned to The Abominable Snowmen was Gerald Blake. This would be his first work on Doctor Who although, in early 1964, he had been scheduled to make an historical adventure called “The New Armada”, which was ultimately dropped. Production on The Abominable Snowmen began with three days, from August 23rd to 25th, at the BBC Television Film Studios in Ealing, London. The first two days were devoted to scenes in the Yeti cave, and the last to model shots. Also recorded at this time was a shot of Padmasambhava's wizened head melting for Episode Six. However, the effect was deemed too horrific, and it was replaced by a more palatable version recorded in the studio.

Cast and crew then embarked on what was, to that point, the longest location shoot ever allocated to Doctor Who. It covered six consecutive days, from September 4th to 9th, and took place at Nant Ffrancon Pass in the Snowdonia Mountains of Wales. Unfortunately, the production was beset by rainstorms, which stymied efforts to film on the first two days and forced the cast and crew to work on September 6th, which had been intended as a rest day. The rain also ensured that there would be no snow on the ground, which Blake had hoped would help sell Snowdonia as a stand-in for the Himalayas. The ground was instead muddy and slippery, causing trouble for the actors -- particularly those in the Yeti costumes -- who found themselves falling frequently. For the Episode Six scene depicting a non-robotic Yeti, a regular Yeti costume was used with its bamboo frame and extra stuffing removed.

Throughout the second half of Season Four, each episode of Doctor Who had been recorded only one week ahead of transmission -- a perilous situation which Lloyd was not keen to repeat. It was therefore decided to tape Episodes One and Two of The Abominable Snowmen on consecutive days: Friday, September 15th and Saturday, September 16th. This would provide a three-week cushion between recording and broadcast. The remaining four installments were then taped on successive Saturdays, beginning on September 23rd and concluding on October 14th. The venue was Doctor Who's regular production home of Lime Grove Studio D in Shepherd's Bush, London.

With the broadcast of Episode One on September 30th, Doctor Who was brought forward to 5.25pm. Juke Box Jury, which had long preceded it, had now been moved to Wednesdays. This meant that Doctor Who would follow Grandstand and a Tom And Jerry cartoon short in the Saturday evening schedules. The news and weather now aired after Doctor Who, and before the chat show Dee Time.

Meanwhile, the Yeti had been a big hit with Lloyd and Bryant, who saw in them the potential for another popular success akin to the Daleks and, more recently, the Cybermen. This had become particularly important now that the efforts of Dalek creator Terry Nation to market an American series based around the mutants from Skaro meant that -- for the time being, at least -- Doctor Who had lost its most enduring monsters. Consequently, even before the recording of The Abominable Snowmen was finished, Haisman and Lincoln had already been commissioned to write a sequel. The Yeti and the Great Intelligence would return in The Web Of Fear.

• Doctor Who Magazine #224, 12th April 1995, “Archive: The Abominable Snowmen” by Andrew Pixley, Marvel Comics UK Ltd.
• Doctor Who Magazine Special Edition #4, 4th June 2003, “Heroes And Villains” by Andrew Pixley, Panini Publishing Ltd.
• Doctor Who: The Complete History #11, 2016, “Story 38: The Abominable Snowmen”, edited by John Ainsworth, Hachette Partworks Ltd.
• Doctor Who: The Handbook: The Second Doctor by David J Howe, Mark Stammers and Stephen James Walker (1997), Virgin Publishing.
• Doctor Who: The Sixties by David J Howe, Mark Stammers and Stephen James Walker (1992), Virgin Publishing.