David Petrie - Head of MI5

Head of MI5

MI5, responsible for defence against espionage, subversion, and sabotage, was near collapse in 1940, riven by internal feuds and overwhelmed with reports of suspected ‘fifth columnist’ activity and demands for security ‘vetting’. Winston Churchill had dismissed its long-serving chief, Sir Vernon Kell, in June, but his temporary successor, A. W. A. (Jasper) Harker, had made little difference. It was Stewart Menzies, head of the Secret Intelligence Service (SIS or MI6), who now put forward Petrie, but Sir David refused to take charge without examining the situation for himself. His report, dated 13 February 1941, revealed that rapid expansion of MI5 (from thirty officers in 1938 to more than 200) had produced haphazard recruitment, inadequate supervision, confusion in the chain of command, and general demoralization. Having emphasized the seriousness of the problem, he agreed to tackle it—on the understanding that the director-general should be master in his own house. Petrie suspected that previous interference by Lord Swinton, chairman of the security executive, had exacerbated factional struggles. He formally took over on 24 April 1941.

The mere presence of Petrie appeared to improve the atmosphere inside MI5. A powerfully built man, with a steady gaze, square jaw, and military moustache, he was straightforward, firm, and decisive, combining a thorough grasp of practical intelligence work with the skills of an unspectacular but effective manager. His manner with subordinates was rather formal; he called even those closest to him by their surnames, and some sensed an air of Scottish puritanism about him. Very industrious, he briefed himself with great care for meetings, where he generally spoke little but to the point. His writing style could be long-winded and pompous, and he made scant effort to cultivate influential people, yet his reliability helped restore official confidence in his top-secret department.

Petrie ended wrangling within MI5 over the new Hollerith punched-card filing method by ruling in its favour, and reorganized the divisional structure of the service to allow its B division to concentrate on counter-espionage. Since autumn 1940 Guy Liddell had been successfully developing the ‘Double Cross System’, whereby captured German spies were used to feed false information to Berlin. There was much friction between MI5 and the SIS over access to decrypted signals intelligence from the Radio Security Service, and Petrie grew exasperated. The two secret services seemed competitive rather than complementary in some matters. MI5 did not operate more than 3 miles outside the British empire, while the SIS managed British intelligence and counter-intelligence in foreign countries. Petrie proposed in April 1942 that the SIS counter-intelligence section should be incorporated into B division of MI5, but prolonged negotiations came to nothing, despite his argument that the ideal demarcation between MI5 and the SIS was functional (defensive–offensive) rather than geographical.

In 1944, after the D-day landings surprised the Germans, Petrie claimed that MI5 had totally defeated enemy espionage in Britain. In reality, their handling of the double agents through the "double cross" operation also perperated extensive and highly successful strategic deception programmes. Post-war study of German intelligence (Abwehr) archives confirmed this. In retrospect, however, this triumph had to be set alongside a serious failure: the inadequate surveillance of Soviet spies. Petrie sensed that the Russian espionage which MI5 uncovered was the tip of an iceberg, but the Foreign Office urged restraint and MI5 had itself already been penetrated, by Anthony Blunt).

Petrie was awarded the KCMG in 1945, as well as American, Dutch, and Czechoslovak orders. Though the new Labour government viewed MI5 with some suspicion, he succeeded in resisting any reduction in its powers or remit. Attlee disregarded his recommendation of Liddell as a successor, however, and appointed Percy Sillitoe as director-general when Petrie retired in 1946.

He died in Sidmouth, Devon, on 7 August 1961.