Sydney Knowles
British military scuba diver
About Sydney Knowles
Lived 1921 – 2012 (aged 90). Sydney Knowles was a frogman.
Sydney Knowles, BEM, (3 September 1921 – 31 July 2012) was a British Royal Navy frogman during and after World War II.
Biography Knowles was born in Preston, Lancashire, the son of a railwayman. He joined the Navy at the start of World War II and served as a stoker aboard the destroyers and , taking part in trans-Atlantic convoys and in Operation Pedestal, the relief of Malta. In 1942 Knowles joined the Underwater Working Party, under Lieutenant Commander Lionel Crabb, at Gibraltar.
In 1955 Crabb took Knowles with him to investigate the hull of the to evaluate its superior manoeuvrability. According to Knowles, they found a circular opening at the ship's bow and inside it a large propeller that could be directed to give thrust to the bow.
Crabb disappeared after a dive on the Sverdlovs sister ship, in Portsmouth harbour in 1956, but 14 months later a body in a frogman suit was found floating off Pilsey Island. The body was mutilated and identification by relatives proved difficult. Knowles knew that Crabb had two prominent scars on his left leg; having failed to find any scars on the corpse he refused to identify it as Crabb's. An inquest jury returned an open verdict but the coroner announced that he was satisfied that the body was that of Lionel Crabb.
On 26 March 2006, The Mail On Sunday published an article by Tim Binding entitled "Buster Crabb was murdered - by MI5". Binding wrote a fictionalised account of Crabb's life, Man Overboard which was published by Picador in 2005. Binding stated that, following the book's publication, he was contacted by Knowles, who now lived in Málaga, Spain. Binding alleged that he then met Knowles in Spain and was told that Crabb was known by MI5 to have intentions of defecting to the USSR. This would have been embarrassing for the UK — Crabb being an acknowledged war hero. Knowles has suggested that MI5 set up the mission to the Ordzhonikidze specifically to murder Crabb, and supplied Crabb with a new diving partner ordered to kill him. Binding stated that Knowles alleges that he was ordered by MI5 to identify the body found as Crabb, when he knew it was definitely not Crabb. Knowles went along with the deception. Knowles has also alleged that his life was threatened in Torremolinos in 1989, at a time when Knowles was in discussions with a biographer.
Knowles also stated on televised interview on that Crabb did not dive alone on his fatal last mission.
He died in Coín, Spain, on 31 July 2012. He was buried in the English Cemetery in Málaga.
Knowles was played by Michael Craig in the fictionalised 1958 film The Silent Enemy about World War II divers in Gibraltar.
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Important facts
People in Sydney Knowles's life
Named in this biography and alive at the same time
Contemporaries
People whose lives overlapped Sydney Knowles's
Frequently asked questions
Who was Sydney Knowles?
British military scuba diver (1921–2012)
When was Sydney Knowles born?
Sydney Knowles was born on 3 September 1921 in Preston.
When did Sydney Knowles die?
Sydney Knowles died on 31 July 2012 in Coín.
What was Sydney Knowles's occupation?
Sydney Knowles was a frogman.
Sources & further reading
Cite this page
APA: Biography.guide. (2026). Sydney Knowles. https://biography.guide/sydney-knowles/
MLA: "Sydney Knowles." Biography.guide, https://biography.guide/sydney-knowles/.
Chicago: "Sydney Knowles." Biography.guide. https://biography.guide/sydney-knowles/.
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