John Leeson, best known as the voice of K9 in Doctor Who, has died aged 83, his son announced on social media. “I regret to announce the death of my father, John Ducker, a.k.a. John Leeson, at 3:03pm today after a summer of illness. The end was peaceful,” he wrote.
No confirmed cause of death was available from the sources reviewed at the time of publication.
Leeson first voiced K9 in the 1977 Doctor Who story The Invisible Enemy, appearing alongside Tom Baker’s Fourth Doctor and Louise Jameson’s Leela. What began as a role in a single storyline became an association that lasted almost half a century.
The mechanical companion’s clipped delivery and familiar “Affirmative” helped make K9 one of the programme’s most recognisable characters. Leeson subsequently returned for K-9 and Company, The Five Doctors and the revived series, including the 2006 episode School Reunion.
His work continued across The Sarah Jane Adventures, the separate K9 television series and numerous audio adventures.
The K9 Job He Thought Would Not Last
Leeson initially doubted that the robot dog would remain in Doctor Who. In a 2025 interview, he recalled how difficult the physical prop could be to operate and wondered whether the demands on expensive studio time would shorten its television life.
Leeson provided the voice, while effects specialist Mat Irvine operated the robot. The actor had also understood that the original booking would not necessarily lead to further work.
Instead, the character became a recurring presence across television and audio, bringing Leeson back to the role long after its original introduction.
One frequently recounted story captured his amusement at that relationship: he anonymously entered a K9 voice imitation competition at an American convention and finished second. The anecdote appears in accounts of his autobiography.
His friendship with Baker also continued beyond the TARDIS. In an interview published by Radio Times on October 16, 2026, Baker discussed their reunion for the Sir Sherlock audio adventures, with Leeson playing Dr Watson opposite his Sherlock Holmes.
Baker described Leeson as supportive and easy to work with, joking: “David Tennant won’t love him like I do!”
The comments were made before the report of Leeson’s death and reflected a working friendship stretching back decades.
Family Life and a Career Beyond Doctor Who
Born in Leicester on March 16, 1943, Leeson used the surname Ducker in his private life. Before entering the profession, he worked in a bookshop and as a porter at Leicester Royal Infirmary. He later trained at the Royal Academy of Dramatic Art.
He married Judy Griffiths on August 2, 1969, at St Mary’s-in-the-Boltons in Kensington, London. An archive photograph of their wedding identifies Judy as a producer’s assistant on the BBC children’s programme Blue Peter. She subsequently worked as a film and television props buyer.
Their son, Guy Ducker, became a film editor and director.
Leeson shared a particularly affectionate family memory in a first-person message published with a licensed K9 toy. He recalled Baker coming to dinner when Guy was seven and insisting on going upstairs to read the boy a bedtime story.
The following day, Guy was reluctant to tell his schoolfriends about the visit: they already doubted his stories that his father was K9 and that Doctor Who came to the family home for dinner.
Leeson’s own family background was far removed from television. In a published interview, he said his father and both grandfathers were clergymen, while his godfather was a bishop. He joked that their experience addressing congregations offered a connection with performing before an audience.
Before becoming K9, Leeson played Bungle in the original 1972 series of Rainbow. His other screen credits included Dad’s Army, Blake’s 7, Sorry! and ’Allo ’Allo!, alongside work as a continuity announcer and a freelance question setter for Mastermind.
Away from broadcasting, he served as a local magistrate for more than 25 years and developed a parallel career as a wine educator under the name John Ducker.
He also published the autobiographical books Flight of the Budgerigar and Tweaking the Tail, followed by the recipe collection Dog’s Dinners.
His association with the long-running Doctor Who franchise remained the most familiar part of that varied career: a performer whose face was often unseen, but whose voice became inseparable from one of its best-loved companions.
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