The TARDIS arrives on Terra Alpha, where the Doctor intends to investigate the iron-fisted rule of Helen A. She has declared negative emotions to be unlawful, and subject to penalties as severe as death. Her edicts are enforced not only by a crack police force known as the Happiness Patrol, but also by a sadistic robot made out of sweets called the Kandy Man. Ace finds an ally in Susan Q, a member of the Happiness Patrol who has become disillusioned with the false jollity of Helen A's regime. Meanwhile, the Doctor befriends a blues player named Earl, and together they confront the horrors of the Kandy Man's Kandy Kitchen.

When Graeme Curry won a screenwriting competition with his radio play Over The Moon, judge Tony Dinner of the BBC Script Unit encouraged him to circulate his work amongst BBC script editors. At the time, Andrew Cartmel was trying to assemble a new stable of writers for Doctor Who, and he invited Curry to a meeting in February 1987. Over the months that followed, Curry struggled to develop suitable ideas for the programme and, despite Cartmel's encouragement, he began to grow discouraged. Finally, during the summer, Curry suggested an adventure set on a planet where unhappy people were persecuted. Cartmel liked the idea, and he helped the writer develop it as a commentary on both modern-day superficiality and the policies of Prime Minister Margaret Thatcher's Conservative government -- as embodied by the tyrannical Helen A. Curry was amused by the notion of the Doctor arriving on a planet, and striving to make the populace unhappy.

The storyline was briefly referred to as The Happiness Patrol but, by the time the first episode was commissioned on September 3rd, it had become “The Crooked Smile”. It would be the studio-bound three-part entry for Season Twenty-Five, which meant that Curry had to ensure that the environment of Terra Alpha could be realised entirely as a collection of sets. He thought in terms of an American-style veneer, complete with vintage Fifties automobiles and colours like a fast food restaurant. When considering the various ways that modern society latched onto ephemeral pleasures, Curry seized upon candies, which offered only fleeting joy in exchange for poor nutritional and dental ramifications. This inspired the Kandy Man, who was envisaged as a cheerful but bored killer, as opposed to one who was cruel and zealous -- one of several instances in which Curry wanted to invert standard expectations.

Graeme Curry suggested that muzak should be heard all over Terra Alpha

Two early notions for “The Crooked Smile” quickly fell by the wayside. Curry suggested that the muzak he loathed should be heard all over Terra Alpha in order to emphasise the fake, antiseptic nature of Helen A's society. Furthermore, the narrative initially took place over several weeks as the Doctor gradually contrived to bring down the government. Once it was agreed that the action should unfold over just a single night, it was decided to have a strong throughline of blues music, since there was concern that the muzak might be too annoying and distracting for viewers.

These changes began to take hold as Curry worked on his last two scripts, which were commissioned on September 30th. Helen A's regime would now be crumbling prior to the Doctor's arrival, while Cartmel also agreed with Curry that the anti-Thatcher spirit should be toned down. To help get a better handle on Ace, Curry joined Ben Aaronovitch -- who was writing the season premiere, Remembrance Of The Daleks -- for a November meeting with Sophie Aldred. Meanwhile, Nathan-Turner encouraged Curry to restore The Happiness Patrol as his story's title.

There were various other amendments as Curry worked on what would turn out to be his only Doctor Who serial. Susan Q was initially tricked into helping Ace escape, rather than doing so willingly. A prison area called Arcadia, complete with dozens of fruit machines and an elaborate go-kart game which the captives would be compelled to play, was replaced with the simpler Waiting Zones. It was originally one of the go-karts which the Doctor hijacked, rather than a Happiness Patrol vehicle. In the Forum, the Doctor and Ace were forced to entertain the audience or be executed; this was excised because it was felt to be too similar to elements of another Season Twenty-Five story, The Greatest Show In The Galaxy.

The director assigned to The Happiness Patrol was Chris Clough, who would also be handling the location-only Silver Nemesis. It was Clough and Nathan-Turner who decided to completely reinvent the visual look of the Kandy Man. In Curry's scripts, the executioner Man was essentially human in appearance, albeit constructed from sugary materials. Clough and Nathan-Turner wanted his robotic nature to be more obvious, and so make-up designer Dorka Nieradzik suggested a costume inspired by Michelin Tires' seminal Bibendum mascot, which literally seemed to be composed of giant sweets. Meanwhile, Richard D Sharp was cast as Earl Sigma. The character had been written as a trumpet player, but it was then learned that Sharp had no experience with the instrument. Instead, Earl would play a harmonica, since it would be less conspicuous that the actor was simply miming along to the soundtrack.

Chris Clough wanted to give The Happiness Patrol a film noir feel

The Happiness Patrol was the last Doctor Who serial to go before the cameras in 1988. Its first recording session took place from July 26th to 28th at BBC Television Centre Studio 3 in White City, London. With many of the sets consisting of streets and building exteriors, Clough found it challenging to plan interesting camera angles. To compensate, he wanted to give the adventure a film noir feel by using various off-kilter and tilted perspectives, as in the 1949 Orson Welles classic The Third Man. This idea was vetoed by Nathan-Turner, who worried that audiences would find the technique too disorientating.

Action on the streets and in the Forum square was taped on all three days. The set for the Waiting Zones was in use on the first two days, followed by the pipes on the last day. It was thought for a time that the Pipe People might be achieved using puppets; eventually, however, eight child actors were hired to play the roles in costume. Conversely, Fifi the Stigorax was actually represented by a trio of puppets. The idea of employing an actor had been dismissed because of the diminutive size Nathan-Turner wanted for Fifi.

The production of The Happiness Patrol -- and Season Twenty-Five as a whole -- then concluded in TC8 on August 10th and 11th. Scenes in the Kandy Kitchen were a major focus throughout. Otherwise, the first day dealt with material in the Happiness Patrol headquarters and Helen A's suite, plus the footage of the dictator which would appear on the Waiting Zone games machine. On the last day, Clough wrapped up the remaining sequences in the pipes, as well as those in the Doompipe and the execution yard. It was expected that the end of recording would mark a changing of the guard on Doctor Who: although it was anticipated that the show would be returning for a twenty-sixth season, Nathan-Turner believed that his long-standing request to be moved onto other projects would finally be granted.

In post-production, all three episodes of The Happiness Patrol were found to overrun severely, and a number of cuts were made. These included a scene in which the Kandy Man sliced off his own finger only to calmly reattach it, Susan Q revealing that she was demoted from Susan L because of a smuggled blues record, the Doctor fleeing the Kandy Kitchen at the start of Episode Two but returning to rescue the captive Earl, and Ace and Susan Q using sniper fire to effect an unsuccessful escape from Daisy K and the Happiness Patrol early in Episode Three. Also dropped was the Kandy Man being overwhelmed by fondant in the Doompipe; Clough was dissatisfied with the execution of the shot. Episode Two originally ended with Daisy K telling Ace that it was “showtime”. This scene was moved to the start of Episode Three, meaning that the revelation of Daisy S's fate now formed the cliffhanger. Clough cast his wife, Annie Hulley, as the Newsreader for what would be his final work on Doctor Who. Having directed eighteen episodes in three years, Clough felt that the time had come for him to move on to new challenges.

The chairman of Bassett Foods complained that the Kandy Man infringed on his company's Bertie Bassett trademark

With Miss Marple having finished its season the week before, the November 2nd broadcast of The Happiness Patrol Episode One was instead followed by the debut of Rockliffe's Folly. On November 10th -- the day following the transmission of Episode Two -- Nathan-Turner received a complaint from HB “Bev” Stokes, chairman and chief executive of Bassett Foods. He objected to the visual appearance of the Kandy Man, on the grounds that it infringed on his company's trademark for their advertising icon, Bertie Bassett. Brian Turner of the BBC Copyright Department informed Stokes on November 25th that his investigation had found no evidence of a transgression on the part of the Doctor Who team, although he did promise that the Kandy Man would not be used again in future storylines.

Bizarrely, this was not the last controversy stoked by The Happiness Patrol. More than two decades later, in February 2010, the anti-Thatcherite slant of Curry's scripts was dredged up by the media in the wake of the intense interest in Doctor Who following Matt Smith's debut as the Eleventh Doctor. Attempts were made to argue that the serial's origins as a political polemic were evidence of a partisan and ideological bias within the BBC. Nothing came of this beyond a few column inches, however, and the would-be scandal dissipated just as quickly as it had materialised.

• Doctor Who Magazine #302, “Archive: The Happiness Patrol” by Andrew Pixley, Marvel Comics UK Ltd.
• Doctor Who Magazine Special Edition #10, 13th April 2005, “Doctorin' The Tardis” by Andrew Pixley, Panini Publishing Ltd.
• Doctor Who: The Complete History #44, 2017, “Story 149: The Happiness Patrol”, edited by Mark Wright, Hachette Partworks Ltd.
• Doctor Who: The Eighties by David J Howe, Mark Stammers and Stephen James Walker (1996), Virgin Publishing.
• Doctor Who: The Handbook: The Seventh Doctor by David J Howe and Stephen James Walker (1998), Virgin Publishing.
• In·Vision #97, August 2001, “Production” edited by Anthony Brown, Cybermark Services.