London in 1892 is protected by Madame Vastra, the so-called “Lizard Woman of Paternoster Row”, her wife Jenny, and the dimwitted Sontaran Strax. It's also home to a fourth enigma: a former traveller in space and time. Unlike Vastra and her associates, however, the Doctor is no longer interested in defending the Earth...

Doctor Who had a long association with the BBC's Children In Need. Since its return to television in 2005, the Doctor Who production team had provided the charity telethon with a variety of exclusive material, including two specially-filmed mini-episodes: the untitled Children In Need (2005) had introduced David Tennant's Tenth Doctor, while 2007's Time Crash had paired Tennant with Peter Davison as the Fifth Doctor. In 2012, it was decided that the time had come for a third such special. Written in August by executive producer Steven Moffat, it would bridge the gap between the departure of companions Amy and Rory at the conclusion of Season Thirty-Three's The Angels Take Manhattan -- to be broadcast in late September -- and the start of the 2012 Christmas special, The Snowmen, in which the Doctor would be depicted as having become a reclusive figure. The mini-episode would also reestablish his former allies -- Vastra, Jenny and Strax -- who had first appeared in A Good Man Goes To War the year before, and would be returning in The Snowmen.

Moffat's script was ultimately christened The Great Detective; this sobriquet was often applied to Arthur Conan Doyle's iconic sleuth Sherlock Holmes, but here referred to Vastra. Directed by Doctor Who producer Marcus Wilson, it was recorded on a street set constructed for The Snowmen. Two sessions were required, on August 23rd and 31st, at the programme's usual Roath Lock Studios facilities in Cardiff. Mark Gatiss -- a regular Doctor Who writer who had also appeared in both 2007's The Lazarus Experiment and 2011's The Wedding Of River Song -- provided the introductory narration.

The Great Detective was broadcast as part of Children In Need on November 16th. It was introduced by Matt Smith and Jenna-Louise Coleman, who also advised viewers that a trailer for The Snowmen would air later that night. The 2012 edition of Children In Need wound up raising almost 27 million pounds for worthy causes.

• Doctor Who Magazine Special Edition #37, Autumn 2014, “The Snowmen” by Andrew Pixley, Panini UK Ltd.