A new book by Ian Cobain has uncovered the murky past of the distinguished academic and medical practitioner and details how Kennedy used brainwashing techniques on Nazi spies during the second world war in an attempt to turn them into double agents.
When Kennedy died suddenly in 1960 at the age of 51 he was professor of psychological medicine at the University of Edinburgh.
The book, Cruel Britannia: A Secret History Of Torture, reveals how just months before his death he delivered a lecture in which he admitted to using brainwashing techniques while carrying out wartime interrogations.
He told the audience that his main object was not the extraction of information, but using a "highly specialised form of stress" to change their loyalties – with the ultimate aim of creating double agents.
Kennedy, who had been commissioned into the army in 1939, was based at the Combined Services Detailed Interrogation Centre in Cairo when he carried out his work.
In his lecture to the Royal Institution of Great Britain, he explained how the use of sensory deprivation was crucial to his technique, which aimed at making the subject become "desperate to escape".
This included the prisoner being kept in a dark, sound-proof room and brought food randomly by silent guards.
The aim was to induce hallucinations triggered by a combination of fatigue or small amounts of drugs such as amphetamines and the use of "ambiguous sound and unstructured visual stimuli".
Kennedy's lecture caused uproar at the time as questions were raised over the use of brainwashing by British forces and led to then prime minister Harold Macmillan insisting that the techniques had "never been used by any organisation responsible to Her Majesty's government".
But the book notes that Macmillan's briefing from the War Office was later amended to include the caveat "as far as the War Office knows".
Author Ian Cobain said: "It seems that Professor Kennedy's experiments in the Middle East caused quite a stir, with some senior intelligence officers flying out from England to watch him at work.
"Exactly how successful he was is less clear. Some of those watching thought he was too slow, and that less subtle interrogation methods should be retained.
"But as far as we're aware, this was the first time that British experiments in brainwashing have been confirmed."
A spokesman for Edinburgh University confirmed Kennedy was a professor at the university, but was unable to comment further as the department which he headed up no longer exists.
The book, which is published this week, investigates Britain's use of torture in the past and present and challenges the official line that the UK does not participate in or condone human rights abuses.
Cobain added: "The most shocking discovery I made was that torture was employed quite widely by the British during the second world war.
"And it seems to have been employed even more readily after the war, both as a means of revenge, and to discover more about the Soviet threat. But my main conclusion is not about the use of torture, but about secrecy – that's what we British are particularly adept at deploying.
"The use of torture by the British is always concealed behind denials and obfuscation and lies. It was in the 1940s, and it is today."