Far in the future, the population of Britain has fled an Earth ravaged by solar flares. But while trying to help a young girl whose classmate has gone missing, the Doctor and Amy discover that something about the mammoth Starship UK is very wrong. The vessel moves even though its engines are idle, holes in the floor divulge enormous tentacles, and the sinister robotic Smilers punish the disobedient. The Doctor finds himself assisted by an enigmatic female vigilante called Liz 10, while Amy learns the truth at the heart of Starship UK... but it's a truth that she can't bear to remember.

After writing The Time Of Angels / Flesh And Stone, the fourth and fifth episodes of Season Thirty-One, Doctor Who executive producer Steven Moffat next turned his attention to the year's second installment. In particular, he wanted this episode to give Amy the opportunity to save the day, preventing the Doctor from making an understandable but terrible mistake, and thereby firmly establish herself as a worthy occupant of the TARDIS. Moffat was also keen to emphasise a fairytale vision of Doctor Who throughout the season. It would be this adventure that would embody that philosophy most fully, landing the Doctor and Amy in the midst of a fantastical, vaguely distorted and slightly sinister version of the real world.

The script ultimately gained the title The Beast Below, and it was paired with the following story, Mark Gatiss' Victory Of The Daleks, as the year's second production block. Assigned to direct Block Two was Andrew Gunn; like the other directors recruited for Season Thirty-One, he was new to Doctor Who, and represented the production team's desire to refresh the programme's visual presentation. Cast in the role of Liz 10 was Sophie Okonedo, who had delivered a standout performance in the critically-acclaimed 2004 film Hotel Rwanda. However, this was not Okonedo's first brush with Doctor Who. In 2003, she had provided the voice of companion Alison Cheney in the animated webcast The Scream Of The Shalka, opposite Richard E Grant as a putative Ninth Doctor. At the time, it was intended that The Scream Of The Shalka would represent the official continuation of Doctor Who -- a plan that was scuppered even before the webcast became publicly available, as the programme's television revival was announced that September.

The first scene shot for The Beast Below was Ian McNeice's cameo as Winston Churchill

The early part of Gunn's recording schedule concentrated on material for Victory Of The Daleks. Consequently, the first scene he shot for The Beast Below was Ian McNeice's cameo appearance as Winston Churchill, which served as a teaser for the subsequent episode. It was recorded at the bunker of the Joint Resilience Unit in Swansea on August 24th, 2009. Two weeks later, Gunn resumed work on The Beast Below. On September 7th, material involving the Doctor and Amy in the Star Whale's mouth was taped at ITV Studios in Cardiff, alongside footage of Amy in the work tent and some green screen shots. Doctor Who's regular studio facilities at Upper Boat hosted the TARDIS scenes on the 8th. September 9th and 10th were spent at the ruins of Neath Abbey, a twelfth-century complex in Neath which posed as the Tower of London.

The key location for The Beast Below was the Johnsey Estates, part of the Mamhilad Park Industrial Estate in Pontypool. On September 11th and 12th, scenes in the voting booth were recorded there. Material in the adjacent waiting area was also taped on the first day, along with footage of Morgan and the Poem Girl which would appear on monitors. Further filming on the second day included the speech given by the younger Liz 10, as well as Peter escorting the Doctor along a back street.

After a day off on the Sunday, it was back to the Johnsey Estates on September 14th. Work began in Mandy and Timmy's classroom, where two of the pupils were played by Gunn's children, Iola and Olen. The team moved on to the waiting area and the Vator, before the day concluded at the Vator Junction. Cameras continued to roll at the latter on September 15th and 16th, but much of Gunn's focus was now on the mammoth London Concourse set, which had taken two weeks to erect and was in use through to the 18th. Nonetheless, some filming was still required in other parts of Starship UK, including the alley with the tent on the 16th and 17th, and the waiting area on the 17th. A busy September 18th also involved recording in the corridors where Liz 10 attacked the Smilers and the Doctor studied the tentacle, in the Vator with Timmy, along the gantry in the lower levels, and in the back street.

After the weekend, September 21st took cast and crew back to Upper Boat for sequences in the Tower of London, the observation deck and the overspill pipe, plus the floor of the Vator opening beneath Timmy. On the 22nd, Gunn's team moved to the Orangery at Margam Country Park in Margam, for material in Buckingham Palace. Lastly, a variety of inserts were shot at Upper Boat on September 23rd. After the end of principal photography, however, Moffat made a number of amendments to the script for The Beast Below. Gunn's schedule did not permit him to participate in the necessary reshoots, and so Doctor Who veteran Euros Lyn -- who had most recently worked on The End Of Time, the final story to feature David Tennant as the Tenth Doctor -- agreed to oversee the additional material, all of which was recorded at Upper Boat.

On November 2nd, Lyn filmed an expanded opening TARDIS scene, with Amy floating in space. It furthered the parallel between the new companion and Wendy Darling, the heroine of JM Barrie's 1904 play Peter Pan; or, The Boy Who Wouldn't Grow Up, who was able to fly to Never Never Land thanks to an application of fairy dust. Alongside numerous inserts, November 4th saw the recording of two major new sequences. In the original script, the Doctor and Liz 10 didn't meet until the monarch rescued him from the Smilers in the overspill pipe. Moffat had now come to feel that the characters needed an earlier encounter, and so he added a scene between them in the Stardrive corridor. Unfortunately, Okonedo was unavailable, so Liz 10 was played by Pina Harrington on this occasion. Moffat also wanted the Doctor and Amy to reflect on the adventure in greater depth during its closing minutes, which inspired a new sequence at the Starship UK window. More pick-up shots were recorded on November 5th and 16th. In between, on the 12th, Lyn remounted the new material in the Stardrive corridor, since Okonedo was now able to work it into her schedule.

The Beast Below aired on April 10th, 2010. With coverage of the Grand National horse racing competition dominating the afternoon schedule on BBC One, Doctor Who was given a 6.15pm start time, five minutes earlier than The Eleventh Hour the week before. As it turned out, however, the equestrian event overran slightly, pushing The Beast Below back to 6.20pm after all.

• Doctor Who Magazine Special Edition #26, 30th December 2010, “The Beast Below” by Andrew Pixley, Panini Publishing Ltd.
• Doctor Who: The Complete History #63, 2017, “Story 204: The Beast Below”, edited by Mark Wright, Hachette Partworks Ltd.