The TARDIS materialises in 1966 London, on the runway at Gatwick Airport. In the Chameleon Tours hangar, Polly witnesses a pilot murder a police detective. But soon after she tells her friends what she saw, Polly goes missing... and when her exact double is found working at the Chameleon Tours kiosk, she denies any knowledge of the Doctor or the murder. Ben soon vanishes too, while Jamie befriends a young woman named Samantha Briggs whose brother disappeared after taking a Chameleon Tours flight. The culprits are faceless aliens, whose theft of human identities is the first step in their conquest of the Earth.

Malcolm Hulke's first contact with the Doctor Who production office came during the programme's formative stages in 1963, when Hulke's “The Hidden Planet” and “Britain 408AD” were both unsuccessful candidates for the show's first season. Likewise, David Ellis had two proposals -- “The Clock” and “The Ocean Liner” -- rejected in early 1966. In March of that year, Hulke and Ellis met and decided to form a writing partnership. It was Ellis who suggested that, together, they might take another stab at Doctor Who. After a false start with “The People Who Couldn't Remember”, which was rejected on June 15th, Ellis and Hulke elected to try again.

The result was “The Big Store”, a four-part adventure which involved aliens taking over a London department store and using it as a front for their invasion of Earth. One group of aliens was a faceless breed, artificially given human features in order to replace people who had been kidnapped in the store. Producer Innes Lloyd and story editor Gerry Davis were happy with the storyline, but thought it would work better if it were transplanted onto an airport setting. Furthermore, Lloyd was unhappy with the strict diet of four-part serials which Doctor Who had recently been following, since they prevented costs from being spread out over more episodes; since the start of 1966, only The Power Of The Daleks had consisted of six installments.

On January 27th, Patrick Troughton was contracted for 23 additional episodes

It was therefore agreed that “The Big Store” would officially be abandoned, and Ellis and Hulke would start again on a new six-part storyline. This attempt would also incorporate Jamie McCrimmon who, in late November, had been a last-minute addition to the roster of companions. The slot it was to occupy was formally extended from four to six episodes on January 2nd, 1967, and “The Chameleons” was commissioned the next day. On January 27th, Patrick Troughton was contracted to play the Doctor in twenty-three additional episodes, beginning with Ellis and Hulke's serial.

Meanwhile, Lloyd and Davis had concluded that Polly and Ben were not working well as companions, and decided to write them out of Doctor Who at the next opportunity. Because of the change in the length of “The Chameleons”, Anneke Wills and Michael Craze were now contracted until part two of the subsequent story, The Evil Of The Daleks. On February 8th, Ellis and Hulke were asked to write the pair out of their adventure's last four installments, with the possible exception of a film sequence for Episode Six, and to introduce a young female character who might be suitable as a new companion. The same was asked of David Whitaker, writer of The Evil Of The Daleks; this gave Lloyd and Davis a choice of potential new regular characters. Wills and Craze were notified that they would not be needed for the first two parts of The Evil Of The Daleks after all, although they would be paid for the entirety of their contracts. Also on February 8th, Frazer Hines' services were secured for both “The Chameleons” and The Evil Of The Daleks.

All of this resulted in a number of changes to the structure of “The Chameleons”. Ellis and Hulke already had a character -- Mary Dawson, introduced in Episode Two -- who could be showcased as a prospective addition to the TARDIS crew. She was able to take over some of the action assigned to Polly and Ben, while Jamie's role was also expanded. In the original version of Episode Two, both the Doctor and Ben investigated the Chameleons' hangar but failed to find Polly, instead being menaced by a falling engine (rather than gas). Ben and Mary then rescued Polly in Episode Three. Now, both Polly and Ben would go missing during Episode Two, after he went to the hangar alone and found her comatose body.

As Ellis and Hulke rewrote their scripts, several other changes were introduced. Mary Dawson became Cleopatra “Cleo” Briggs and then Samantha Briggs, Quinn was renamed Blade, Nurse O'Brien became Nurse Pinto, and Pied Piper Tours was rechristened Chameleon Tours. The writers had set “The Chameleons” at London Airport (as Heathrow was then known), and approaches were made on February 9th to secure permission to film there. However, it was ultimately decided to accept an offer to use the premises of Gatwick Airport, near Horley in Surrey. Formal clearance was obtained from the British Airports Authority on March 2nd, by which time the serial was retitled The Faceless Ones.

Peter Bryant was made an associate producer beginning with The Faceless Ones

By now, Lloyd had made it known that he wished to leave Doctor Who. He was never particularly enamoured of science-fiction and, after a year on the programme, he was eager for new challenges. Davis was offered a promotion to producer, but he instead decided that he, too, wanted to move on from the show. Former BBC Radio producer Peter Bryant was brought onto the production team around the end of 1966 to serve as Davis' assistant, and it was felt that he might be a suitable replacement for Lloyd. As such, Bryant was made an associate producer beginning with The Faceless Ones so that he could gain experience with television production.

The director assigned to The Faceless Ones was Gerry Mill, who had worked as a production assistant on The Massacre Of St Bartholomew's Eve a year earlier. The Faceless Ones would be Mill's only Doctor Who story as a director. Mill cast Pauline Collins in the role of Samantha Briggs. Lloyd asked Collins if she was interested in becoming a regular on Doctor Who but the actress declined, stifling any consideration of Samantha as a new companion. Also appearing in The Faceless Ones was Gilly Fraser as Ann Davidson, the Chameleon Tours stewardess; Fraser was married to Peter Purves, who had played companion Steven Taylor in 1965 and 1966.

Filming at Gatwick Airport began on March 10th and continued on the 13th, 14th and 17th. This material included Ben and Polly's farewell scene for the end of Episode Six. In between, production moved to the BBC Television Film Studios in Ealing, London, where model filming took place on March 15th and 16th. These days marked the culmination of problems with Shawcraft Models, the outside contractors who had handled much of Doctor Who's prop demands since the series' debut. Discontent with Shawcraft's work had been brewing in the production office for a while, and was exacerbated by the firm's delivery of the huge, costly and almost immobile Macra prop for The Macra Terror at the start of March.

For The Faceless Ones, Shawcraft built the Chameleons' plane and satellite. Unfortunately, the door to the satellite did not work properly, and the bulb on its base blew, with no replacement on hand. Most severely, Shawcraft had not considered how the satellite should be mounted and, when they finally suggested hanging it from a wire, the model proved too heavy and fell to the floor. Shawcraft was able to refurbish the prop overnight, but only at the expense of several hours of work by Mill's team. Then, during the last day at Gatwick, another Shawcraft-built prop -- Spencer's freezing gun -- broke, and it took the company several days to repair it. All of this led to the decision to cease utilising Shawcraft's services. The Doctor Who production office would instead turn to the BBC's own Visual Effects Department, which had rescinded the concerns it had voiced in 1963 that it would be unable to handle the programme's demands.

As usual, The Faceless Ones was taped on consecutive Saturdays at Lime Grove Studio D in Shepherd's Bush, London. In a break with convention, Mill decided to tape scenes out of script order on several occasions. Episode One went before the cameras on April 1st. On the 5th, Michael Peacock, the Controller of Programmes for BBC One, informed Lloyd that Doctor Who had been renewed for a fifth season. However, his request to move from the antiquated Lime Grove back to Riverside Studio 1 -- which had previously been Doctor Who's production home -- was denied, since those facilities had now been earmarked for the retooled Z Cars.

On April 8th, Wills and Craze attended their final Doctor Who recording session, their only remaining scene having been pre-filmed at Gatwick. This day also saw the debut of a new version of the Doctor Who theme music, once again arranged by Delia Derbyshire, and designed to better suit the new title sequence which had been introduced with The Macra Terror. A remount of some of the model shots took place at Ealing on April 11th, using an improved satellite prop. Worrisomely, on the 13th, Peacock suggested that Doctor Who's fifth season should be its last. He discussed replacing it in 1968 with a new series called Bonaventure, which had been recommended by Shaun Sutton, the Head of Serials; however, nothing would come of this.

Ellis and Hulke had intentionally designed their scripts for The Faceless Ones so that, in instances where both the original human and the Chameleon duplicate were required to appear in the same episode, one would appear only in studio scenes while the other would feature exclusively in location filming. The sole exception was the discovery of Nurse Pinto and her duplicate together in Episode Five, a sequence taped on April 29th. In this case, the effect was created via a combination of photographic stills, careful camera placement, a recording break, and an extra in make-up. This day also provided Hines with an opportunity to use his natural accent, as he dropped his Scottish brogue for his appearances as Jamie's Chameleon duplicate. Recording on The Faceless Ones concluded on May 6th.

• Doctor Who Magazine #212, 11th May 1994, “Archive: The Faceless Ones” by Andrew Pixley, Marvel Comics UK Ltd.
• Doctor Who Magazine Special Edition #4, 4th June 2003, “Good Vibrations” by Andrew Pixley, Panini Publishing Ltd.
• Doctor Who: The Complete History #10, 2017, “Story 35: The Faceless Ones”, edited by Mark Wright, 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.