Doctor Who/The Sea Devils

The Sea Devils
Season 9, Serial 3
Airdate	February 26, 1972
Production Number	LLL
by	Malcolm Hulke
Directed by	Michael Briant
← 9x02 The Curse of Peladon	9x04 → The Mutants
Doctor Who — Season Nine

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The Sea Devils is the third serial of the ninth season of Doctor Who, and the sixty-second serial overall.

Episode One: Jon Pertwee (Doctor Who), Roger Delgado (Master), Katy Manning (Jo Grant), Edwin Richfield (Captain Hart), Clive Morton (Trenchard), Royston Tickner (Robbins), Neil Seiler (Radio Operator), Declan Mulholland (Clark), Hugh Futcher (Hickman), June Murphy (3rd Officer Jane Blythe), Alec Wallis (Ldg. Telegraphist Bowman), Brian Justice (Castle Guard Wilson), Terry Walsh (Castle Guard Barclay), Pat Gorman (Sea Devil)

Episode Two: Jon Pertwee (Doctor Who), Roger Delgado (Master), Katy Manning (Jo Grant), Edwin Richfield (Captain Hart), Clive Morton (Trenchard), June Murphy (3rd Officer Jane Blythe), Eric Mason (C.P.O. Smedley), Declan Mulholland (Clark), Pat Gorman (Sea Devil)

Episode Three: Jon Pertwee (Doctor Who), Roger Delgado (Master), Katy Manning (Jo Grant), Edwin Richfield (Captain Hart), Clive Morton (Trenchard), Donald Sumpter (Commander Ridgeway), David Griffin (Lt. Commander Mitchell), June Murphy (3rd Officer Jane Blythe), Christopher Wray (Ldg. Seaman Lovell), Stanley McGeagh (Castle Guard Drew), Terry Walsh (Castle Guard Barclay)

Episode Four: Jon Pertwee (Doctor Who), Roger Delgado (Master), Katy Manning (Jo Grant), Edwin Richfield (Captain Hart), Clive Morton (Trenchard), Donald Sumpter (Commander Ridgeway), David Griffin (Lt. Commander Mitchell), June Murphy (3rd Officer Jane Blythe), Alec Wallis (Ldg. Telegraphist Bowman), Colin Bell (C.P.O. Summers), Brian Vaughan (Lt. Commander Watts), Stanley McGeagh (Castle Guard Drew), Pat Gorman (Sea Devil)

Episode Five: Jon Pertwee (Doctor Who), Roger Delgado (Master), Katy Manning (Jo Grant), Edwin Richfield (Captain Hart), Donald Sumpter (Commander Ridgeway), David Griffin (Lt. Commander Mitchell), Colin Bell (C.P.O. Summers), Christopher Wray (Ldg. Seaman Lovell), Rex Rowland (A/B Girton), Martin Boddey (Walker), Norman Atkyns (Rear Admiral), June Murphy (3rd Officer Jane Blythe), Alec Wallis (Ldg. Telegraphist Bowman), Peter Forbes-Robertson (Chief Sea Devil), Pat Gorman (Sea Devil)

Episode Six: Jon Pertwee (Doctor Who), Roger Delgado (Master), Katy Manning (Jo Grant), Edwin Richfield (Captain Hart), Martin Boddey (Walker), John Caesar (C.P.O. Myers), June Murphy (3rd Officer Jane Blythe), Alec Wallis (Ldg. Telegraphist Bowman), Peter Forbes-Robertson (Chief Sea Devil), Pat Gorman (Sea Devil)

Trivia

The Show

• Every episode ends with the following text:

The BBC wish to acknowledge the help given to them by the Royal Navy in the making of this programme

• First appearance of the Sea Devils who would not only make multiple more appearances throughout the series, but even be the subject of the spin-off series The War Between the Land and the Sea.

• A re-edited version of this serial was broadcast on December 7, 2025 on BBC Four ahead of the launch of the spin-off series. It even includes a re-dub to tie into the spin-off where as the Chief Sea Devil’s line "We shall be the victors in the war against mankind." is now "We shall be the victors in the war between the land and the sea."

• One of the few stories in the series (11 to date) not to feature the TARDIS.

Behind the Scenes

• After the show aired, MI5 came to the studio asking how they came up with the nuclear submarine model. Briant and the visual effects designer explained that they simply used an off-the-shelf model kit, but replaced the propeller with a vacuum cleaner part because the model’s propeller didn’t look seaworthy. By sheer happenstance, the vacuum cleaner part had the exact same number of blades as the real nuclear submarine's propeller, meaning they accidentally guessed classified information that revealed the sonar signal that identified British nuclear submarines.

Goofs

• When the Doctor and Jo enter the minefield and stop for the Doctor to take out his sonic screwdriver, a boom mic appears in the lower left-hand side of the screen.