The TARDIS lands amidst the waters of the North Sea in the modern day. Coming ashore, the Doctor, Jamie and Victoria detect the sound of a heartbeat in a pipeline connecting rigs off the coast to a nearby refinery. The time travellers learn that the refinery has been plagued by problems: the pipeline pressure keeps dropping, and there is intermittent loss of contact with the rigs. The strain is taking its toll on Robson, the head of the refinery, but his assistant, Harris, is troubled by a mysterious attack on his wife. The Doctor realises that a parasitic seaweed has invaded the pipeline, and is preparing to take control of all humanity.

On September 24th, 1964, Doctor Who story editor David Whitaker rejected a proposal from writer Victor Pemberton entitled “The Slide”, concerning a sentient form of mud which took over a group of villagers. Pemberton had also submitted a version, excluding Doctor Who elements, to BBC Radio. There it found favour with producer Peter Bryant, and was eventually broadcast during February and March 1966. The following year, Bryant became the story editor of Doctor Who and Pemberton was hired as his assistant. After three months, Pemberton decided to return to freelance writing, and proposed that he craft a new Doctor Who serial which would resurrect elements of “The Slide”.

As a result, “The Colony Of Devils” was commissioned by Bryant on October 5th, 1967. Instead of living mud, Pemberton took inspiration from the nation's emerging interest in natural gas, which had recently been discovered in abundant quantities beneath the North Sea. The invading force would now be sentient seaweed which thrived on the gas. This, in turn, prompted a change in setting from a British hamlet to a North Sea refinery.

Derrick Sherwin felt that several major script changes needed to be made

“The Colony Of Devils” was intended to follow The Enemy Of The World in the season schedule. However, in late 1967, Bryant was appointed the new producer of Doctor Who, with Derrick Sherwin taking over as story editor. Sherwin was less enamoured of Pemberton's scripts, and felt that several major changes needed to be made. To provide time for these rewrites, “The Colony Of Devils” was pushed back one spot in the recording schedule, with The Web Of Fear brought forward to replace it.

It was at this stage that a major story strand in Episodes Four and Five was entirely removed; this involved the Doctor failing to prevent the Weed from using toxic gas, transmitted along the pipeline, to kill the attendees of a conference near the refinery. In Episode Five, Victoria's screams were to have killed Oak's partner -- who, at this point, was named Swan. It was Jamie who finally defeated the Weed at the story's climax by playing his bagpipes. Sherwin generally toned down the spookiness of the Oak and Swan double-act, which Pemberton had imagined as a grim parody of the classic comedy pairing of Stan Laurel and Oliver Hardy. He also decided that Swan should survive, and used Victoria's amplified screams to kill the Weed instead of the bagpipe music.

In late 1967, another major change was needed when it became known that Deborah Watling would be leaving Doctor Who with “The Colony Of Devils”. Sherwin duly inserted material into the scripts to build up to Victoria's departure. Several characters were renamed to avoid confusion with recent adventures: Swan became Quill (there having been a Swann in The Enemy Of The World), while the presence of a Corporal Blake in The Web Of Fear prompted the renaming of the same-surnamed individual in “The Colony Of Devils” to Price. Less significantly, Lutyens was modified slightly to Van Lutyens.

Pemberton was initially very unhappy about Sherwin's changes, and considered having his name taken off the scripts. Ultimately, however, he accepted the story editor's decisions regarding what turned out to be his only televised Doctor Who serial, and even considered spinning Oak and Quill off into their own project. Pemberton was also able to contribute some ideas to the revised drafts, such as the notion of the TARDIS landing at sea. Originally, it had materialised on the edge of a cliff, but this was felt to be too similar to the end of The Rescue, three years earlier.

The director assigned to “The Colony Of Devils” was Hugh David, making his second and final Doctor Who serial, following The Highlanders the previous season. David's first order of business was the location shoot, which took place from February 4th to 6th, 1968. All three days were split between two venues: the Red Sands Sea Fort in the Thames Estuary stood in for the rig, while material on the beach was recorded at Botany Bay in Broadstairs, Kent. Made nervous by the close proximity of the cliffs, Patrick Troughton refused to participate in the sequences involving the helicopter, and so he was doubled in some shots by pilot Mike Smith.

As scripted, it was intended that the Doctor use a regular screwdriver when he inspected the pipeline on the beach. However, production assistant Michael Briant -- later a Doctor Who director himself on several serials beginning with Colony In Space in 1971 -- suggested that this part of the narrative would be more interesting if the Doctor instead wielded a special screwdriver which operated using soundwaves. Visual effects designer Peter Day duly prepared a prop for the “sonic screwdriver”. However, the winter weather was so cold that Troughton kept dropping it, and so the whistle from Deborah Watling's life jacket was used instead. Nonetheless, the sonic screwdriver would endure and become a beloved part of the Doctor Who mythos.

Cast and crew next moved to the BBC Television Film Studios in Ealing, London, where work spanned February 7th to 9th. Most of the scenes recorded at this time were those which required use of the BBC's foam generator, particularly those in the impeller shaft. A fourth location day was then needed on February 12th at the Denham Aerodrome in Denham, Buckinghamshire. The objective was to capture close-ups of the Doctor, Jamie and Victoria in the helicopter -- which, to Troughton's relief, could stay on the ground. It was around this time that the serial was retitled Fury From The Deep, to avoid any Satanic implications.

The first five episodes of Fury From The Deep followed the usual Doctor Who production pattern, with each installment taped on successive Saturdays at Lime Grove Studio D in Shepherd's Bush, London. Episode One went before the cameras on February 24th. On March 5th and 6th, David's team returned to Ealing to film the climactic battle against the Weed for Episode Six. Some of the material from Episode Four was remounted on March 23rd, alongside the recording of Episode Five.

March 29th marked the end of Deborah Watling's regular involvement in Doctor Who

The concluding installment of Fury From The Deep saw the production shift to Studio 1 at the BBC's Television Centre in White City, London. The antiquated confines of Studio D had never been well-suited to a programme with the technical complexity of Doctor Who; the more modern Television Centre would now be the programme's principal home for the rest of the fifth recording block. The change of venue meant that Episode Six would be taped on a Friday, March 29th. Although footage recorded for Fury From The Deep would be used to provide a final glimpse of Victoria during the opening moments of the next story, The Wheel In Space, this day marked the end of Deborah Watling's regular involvement in Doctor Who.

With the broadcast of Fury From The Deep Episode One on March 16th, Doctor Who was moved back to 5.15pm -- its original timeslot. It now followed directly after Grandstand; there would no longer be a Tom And Jerry cartoon short separating the two programmes. The first three episodes were still followed by a news update and then The Monkees. However, these were interchanged as of February 24th, the day that Episode Four was transmitted.

• Doctor Who Magazine #277, 5th May 1999, “Archive: Fury From The Deep” by Andrew Pixley, Panini UK Ltd.
• Doctor Who Magazine Special Edition #4, 4th June 2003, “Heroes And Villains” by Andrew Pixley, Panini Publishing Ltd.
• Doctor Who: The Complete History #12, 2018, “Story 42: Fury From The Deep”, 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.