John Quine: Counter-intelligence supremo at MI6 who exposed the double agent George Blake

John Quine was head of counter-intelligence at the British Secret Intelligence Service MI6 in the 1960s, and one of the team that extracted a confession of treachery from the double agent George Blake. Blake, a member of MI6, was, of all the spies uncovered in the Cold War, the one who did most damage to Britain. He received, in 1961, the longest jail sentence ever given out in a British court – 42 years – but did only five in Wormwood Scrubs before escaping in 1966 to Moscow via East Berlin, to which he was driven hidden inside an accomplice's family camper van.

Quine had a personal interest in Blake's unmasking, since of the at least 40 British agents killed in Communist Eastern Europe after being exposed by Blake to the Soviet Russian secret police, the KGB, many were Quine's appointees. So closely was Quine familiar with the workings of Blake's mind that he warned, after a visit to interrogate Blake further in prison, that Blake was plotting to get out and might do it – but was disbelieved.

The interrogation in the spring of 1961 that ensured Quine's life would ever after be remembered with Blake's took place at an elegant mansion in Carlton Gardens in central London. Quine was accompanied in the task by SIS colleagues Terence Lecky, just returned from Zurich, Harold Shergold, formerly head of stations in West Germany, and by a former police officer, Ben Johnson.

The men had sought advice on 20 March from MI6's Director D, Martin Furnival Jones, on whether to offer Blake immunity from prosecution in return for a confession, before summoning him back for supposed administrative reasons from a language course he was attending in Lebanon. But that would have been the last thing they wanted to do – and to their relief, it took them only two weeks, until the afternoon of 5 April, to get Blake to admit that he had offered his services to the KGB in October 1951 in Korea, where he had been posted under cover of being a British diplomat, and where he was interned by the Communist north during the 1950-53 Korean War. The details are recorded by Professor Christopher Andrew in The Defence of the Realm: the Authorized History of MI5 (2009).

The spymaster's life is linked in other ways to his quarry, the traitor's: Quine, only two years older than Blake, shared with him a naval start to his career, and his way forward, too, was determined by events in the Far East. But there the similarities end. Where Blake began his working life in the Second World War by joining up as an ordinary seaman, Quine was commissioned into the prestigious Royal Naval Volunteer Reserve, joining Coastal Forces as a Motor Torpedo Boat officer, to pursue daring night actions attacking enemy convoys.

Where Blake was of foreign parentage, naturalised British, and joined the Dutch resistance, arriving from across the Channel only in 1940, Quine spent his childhood in Britain, a Dumfriesshire country doctor's son who later grew up in Kent. And where Blake's two-year Korean prison ordeal so broke his morale that he turned traitor, Quine learned success as the voice of the victor – from 1946 in Tokyo debriefing in Japanese, for Japan's American occupiers, senior figures suspected of war crimes.

John Quine was born in Gretna, Scotland, before his family moved to Seasalter, Kent, and he later attended Faversham Grammar School and went to university at King's College London. He was commissioned into the RNVR in February 1942, and is known to have taken part in an attack off the Dutch coast by the 11th MTB Flotilla on 13 September 1943, when five MTBs made a pincer movement against an enemy convoy under a near-full moon, but neither sank nor damaged any. This was made good on the night of 9 and 10 December, off Ijmuiden, however, when Quine and his fellow officers, firing their torpedoes from different angles, achieved two explosions on an enemy convoy's largest ship – and had the satisfaction of seeing their targets left in confusion, ships shooting at one another in the dark.

Towards the end of the Second World War, Quine answered a government appeal for volunteers to learn Japanese, and took a language course in 1944 in the United States at the University of Colorado. He joined MI6 in 1945, the year after Blake, and was posted to Tokyo from that year until 1954. Quine then moved to Warsaw, and was credited with setting up the network of British intelligence in the Communist German Democratic Republic that Blake was to destroy. A later posting was Lebanon, and Quine became Head of Counter Intelligence in London in March 1961.

After the Blake episode he worked for MI6 in Africa, including South Africa, in the late 1960s, followed by a stint in Mauritius, before retiring in 1975. In his leisure he read again the James Bond books by Ian Fleming that he had always enjoyed – and this prompted him to buy a house that Fleming had once lived in: the Old Palace, Bekesbourne, in Kent. Quine lived there with his family – his wife, Heather, whom he had married in 1946, and three sons, two of whom were born in Tokyo – until he and Heather separated in the 1980s.

Friends remembered him as an energetic presence, who made several attempts to get business projects off the ground, but without much success. He married again, and is survived by his second wife, Pat, and his sons.

Anne Keleny

John Quine, spymaster: born Gretna, Dumfriesshire 13 September 1920; married 1946 Heather Martin (died 2005; three sons), secondly Pat; died 29 April 2013.