Strange things are happening in 1953 London, in the days leading up to the coronation of Queen Elizabeth II. Mr Magpie is practically giving away television sets, despite the fact that they're the cutting edge of new technology. Black-suited policemen are taking away people in the middle of the night. And something is turning normal men and women into faceless monsters. It's up to the Doctor to stop the Wire from killing millions, even as Rose becomes its latest victim...

Mark Gatiss had scripted The Unquiet Dead for the new Doctor Who series' inaugural season, and was eager to return to the programme. In January 2005, Davies presented Gatiss with a story idea which he thought would present a challenge: an historical adventure (as was Gatiss' preference), but one set in the 1950s, an era more recent than the writer was usually comfortable with. Entitled “Mr Sandman”, Davies' concept was of an alien intelligence existing within a contagious song; those infected by the melody become faceless creatures.

Gatiss began writing a treatment called “Sonic Doom”, set at the dawn of the rock 'n roll era of the late Fifties. However, it was eventually agreed that the idea of a living song did not translate sufficiently well to television. As Gatiss was a fan of television's history, it was decided to have the alien force inhabit a broadcast signal instead. The story -- at this point generically referred to as “1950's” -- would now be set in 1953, at the time of Queen Elizabeth II's coronation, since this was an event which instigated a substantial upsurge in the number of British households owning television sets. Gatiss hit on the idea of patterning his villain's guise after Sylvia Peters, who had been one of the BBC's primary continuity announcers from 1947 to 1958.

One of the seminal television events of the Fifties had been the broadcast of The Quatermass Experiment in 1953. Gatiss wanted to incorporate numerous homages and references to Nigel Kneale's opus in his scripts, but ultimately only the clenching hands of the faceless victims survived. (Coincidentally, Gatiss was appearing in a live remake of The Quatermass Experiment alongside David Tennant while writing for Doctor Who. During rehearsals, Tennant revealed to Gatiss that he would be taking over the lead role in Doctor Who, enabling Gatiss to get a jump start on writing for the Tenth Doctor. To this stage, Gatiss' script had been written with Christopher Eccleston's Ninth Doctor in mind.) Also deleted was a subplot in which Rose visits her aunt, who works on a game show for the BBC; Davies feared that having the Corporation be too involved in the plot would make the episode difficult to take seriously.

One in-joke which did survive was Gatiss' decision to give the name “Florizel Street” to the road on which the Connollys live. This had been the working title of the long-running ITV soap opera Coronation Street (and at one point, at the story's conclusion, the Doctor would have taped over the Wire with an installment of Coronation Street itself). Initially, though, the scripts had been set not on Florizel Street but on Powell Street, intended to be the same location where Rose Tyler's apartment block, the Powell Estate, would later be built. However, since Rose's home had already been established as being situated in the south of London, this would make setting the climax at Alexandra Palace a more cumbersome plot element.

Magpie was conceived by Gatiss as a more malevolent figure; his villainous nature was toned down at Davies' suggestion. The entrance to Bishop's headquarters was originally concealed by a newspaper vendor rather than a market stall. The street party in the last scene was intended to be set at night, complete with fireworks; this was altered as it was felt to be too similar to the conclusion of Fear Her later in the season. Also cut from the script was Tommy's grandfather (who appeared in place of his grandmother in one draft), a much longer chase scene involving the Doctor's Vespa which included action in the London Underground, and a climactic scene of the television sets in Magpie's shop exploding after the defeat of the Wire.

Searching for a title for his episode, Gatiss contemplated “The One-Eyed Monster”, as this had been the name of an installment of the mid-Seventies children's series The Kids From 47A which had involved a TV addict. He subsequently rejected this because he felt it conjured phallic connotations, and finally opted for The Idiot's Lantern, which was contemporary slang for a television set. This title was suggested by Gareth Roberts, who had written the interactive episode Attack Of The Graske and was contributing the TARDISodes to the whole of the second season.

The Idiot's Lantern had originally been slated as the ninth episode of the season, after The Impossible Planet / The Satan Pit. It was bumped up to seventh, preceding the two-parter, when The Runaway Bride was held back to serve as the 2006 Christmas special, ensuring that two multi-episode stories weren't scheduled consecutively. In terms of production, The Idiot's Lantern was intended to be a single-episode Block Five, with The Impossible Planet / The Satan Pit forming Block Four. When these scripts encountered delays, however, it was decided that The Idiot's Lantern would instead join Fear Her in comprising the fourth production block. The unexpected shift in his deadline meant that Gatiss had to hurriedly finish writing his episode.

Directing The Idiot's Lantern was Euros Lyn, who had already handled Tooth And Claw and The Girl In The Fireplace earlier in the season. Because of Maureen Lipman's limited availability, Lyn's first piece of filming occurred on January 23rd, 2006, in Wood Green, London, at Alexandra Palace itself. In addition to filming Lipman's role as the Wire, some exteriors of the building were also shot. Recording on Florentia Street in Cathays, Cardiff -- posing as Florizel Street -- then took place from February 7th to 9th. The exterior of Magpie Electricals, meanwhile, was actually on Blenheim Road in Pen-y-lan, Cardiff; shooting there took place on the 10th.

Three days at the Doctor Who studio space of Unit Q2 in Newport then ensued. Covering material in the Connolly house, this spanned February 13th to 15th. Another day at Florentia Street followed on the 16th. At the same time, the Connolly house set at Unit Q2 was used for recording the episode's TARDISode. This also featured Margaret John as Tommy's grandmother, and depicted her being attacked by the Wire. Originally, writer Gareth Roberts had conceived a TARDISode in which the Wire travels between empty sitting rooms in search of a victim.

On February 17th, the Cardiff Royal Infirmary stood in for Alexandra Palace, while the sequences atop the transmitter itself were actually performed on the Veritair Limited tarmac at the Cardiff Heliport on Cardiff Bay. Bishop's lair was really the South Dock of the Newport Docks; filming took place there on the 20th and 21st. Production on The Idiot's Lantern then wrapped up back at Unit Q2, where scenes in Magpie's shop were taped on the 22nd and 23rd.

• Outpost Gallifrey: New Doctor Who Series News Page, edited by Shaun Lyon.
• Doctor Who Magazine Special Edition #14, 9th November 2006, “Episode 7: The Idiot's Lantern” by Andrew Pixley, Panini Publishing Ltd.