England’s cabinet noir for intercepting and reading private and diplomatic correspondence, the Decyphering Branch, had been abolished in 1844 after parliamentary protests at the opening of the correspondence of the exiled Italian nationalist Giuseppe Mazzini and the sharing of their contents with the Austrian and Neapolitan governments. Perlustration was not resumed for seventy years. At the outbreak of hostilities in 1914, the Post Office (which was a government department, headed by a minister, the Postmaster General) employed a single censor intercepting, opening, reading and resealing suspect letters. By the Armistice in 1918 the Censor’s Office employed over 2,000 staff, who were expected to open at least 150 letters a day each.
At the outset of war MI5 comprised Kell, six officers, its chief detective William Melville (formerly the Metropolitan Police superintendent in charge of Special Branch), two assistant detectives, six clerks and a caretaker. Its initial priority was to catch spies and saboteurs; but from 1916–17 its political masters were equally anxious about civil unrest and subversion. By 1918 MI5 had a staff of over 800, including 133 officers. Jervis would have rhapsodized at the amplitude of their records: over 250,000 index-cards cross-referencing 27,000 personal files in its central registry by the time of the Armistice that halted the European war in November 1918. Similarly Kell’s counterpart at SIS, Sir Mansfield Cumming, numbered his staff (exclusive of agents) as 47 in June 1915 and 1,024 by October 1916.
The months after the Armistice were a time of political instability, strange alliances and imponderable risk. Exterior perceptions might mislead. In the east London slum district of Limehouse, during the last months of the war, Irish nationalists combined with socialists to organize a militant constituency cohort led by a pharmacist called Oscar Tobin. One day in January 1919 a newly demobilized soldier, carrying a nondescript suitcase like the terrorist in Conrad’s Secret Agent, visited Tobin’s shop, went up the backstairs with him and laid plans for socialists to take control of Stepney Borough Council. Tobin was a Jewish Romanian who was to be refused naturalization as a British subject in 1924. To a watcher the confabulation above his shop might have seemed the inception of a revolutionary cell; but the demobbed soldier was Clement Attlee, and this was the first step in a political career that always upheld constitutionalism and culminated in his leadership of his country during the Cold War. History is full of misleading appearances. The balance between trust and treason, as Queen Elizabeth said, is seldom easy to get right.26
At the acme of dynastical insecurity in November 1918, when the monarchies in Austria, Bavaria, Hungary, Prussia, Saxony and Württemberg followed the Romanov empire into extinction, Sir Basil Thomson, the bristling, pushy head of Special Branch at Scotland Yard, wrote a memorandum intended for the eyes of King George V. ‘Every institution of any importance has depended during the war for its existence on an intelligence organization,’ he began with his usual bounding confidence. The Foreign Office, the Admiralty, the War Office and the Ministry of Blockade all had departments collecting data, evaluating rumours, making predictions and trying to stabilize the future. Additional officials in Downing Street were amassing political intelligence for the Prime Minister, Lloyd George. His predecessor, Asquith, had fallen from power in 1916, Thomson continued, ‘not so much because he failed in policy, as because he had no intelligence organization to keep him warned of the intrigues and movements around him’. Similarly, among factors in the recent Russian revolution and overthrow of the Romanov dynasty, defective intelligence had a leading part: ‘Petrograd was in the hands of the revolutionaries before any hint of trouble was heard at Tsarsky’ (Tsarskoye Syelo, the imperial compound outside the capital). Thomson’s lesson for the Royal Household was terse:
(1) The only safe organizations are those that possess an efficient intelligence system.
(2) Those persons or organizations that have failed to develop such systems have been destroyed.
Statecraft had mutated. Europe’s age of intelligence had begun.1
Opposing power blocs had different explanations for these new necessities. Soviet Russia attributed the world’s great changes to the communist revolution of 1917, and to the irresistible impetus towards the dictatorship of the proletariat. The European powers attributed them to the convulsion of continental warfare in 1914–18. Certainly the clashes of the Russian, British, German and Austro-Hungarian empires, and of the French and American republics, had changed their governments’ attitudes to their populations. For centuries monarchs had levied troops to fight wars, governments had repressed civil disorder and reformers had tried to harness popular sentiments. But the military, industrial and transport mobilization of 1914–18 turned the civil population into a new concept called manpower. People of working age – women as well as men – were deployed as a war resource in factories and transport systems as well as on battlefields. The Defence of the Realm Act was enacted in London in 1914, and extended at intervals so as to manage the mass of adults to an unprecedented extent.
When the Russian revolution erupted in 1917, MI5 was focused on German espionage, subversion and sabotage. With the start of the Comintern’s international activities and the foundation of the CPGB in 1920 it changed target to Bolshevism. It relied on the police officers of the Metropolitan Police’s Special Branch, which chewed communists, anarchists, Indian nationalists, pacifists, atheists, self-important but insignificant cranks, Soho rakes, unemployed marchers and mutinous merchant seamen in its greedy, indiscriminate maw. Special Branch reports were often unimaginative if not obtuse. ‘I should wait a long, long time before acting on the advice of the present authorities at Scotland Yard,’ wrote a Tory MP, Sir Cuthbert Headlam, at the time of a botched police raid on the offices of the Soviet trading agency ARCOS in 1927. Special Branch lost control of monitoring domestic subversion after the discovery in 1929 that it had been betrayed by two Bolshevik informants, Hubert van Ginhoven and Charles Jane. Complicated cross-jurisdictional clashes between MI5 and SIS were considered at ministerial level by the Secret Service Committee in 1919, and again by senior officials in 1921, 1922, 1925 and 1927. Committee members found it hard to adjudicate between the two agencies. A resolution was not reached until Kell’s organization was named as the lead national security service in 1931.2
MI5 was primarily an advisory agency, which existed to inform government decisions and to assess and manage risks. Its staff collected, filtered, indexed and filed information gleaned from confidential informants, passport and customs officers, intercepted mail, the garbled chatter heard by covert bugging of offices and telephones, watching of addresses, shadowing of individuals and surveillance of bank accounts, public meetings and publications. Counter-intelligence officers used this data to assess the risks posed by individuals who might be subversives or spies. They resembled historians scouring documentary fragments, unravelling confused memories, checking false trails, re-evaluating doubts and discounting persecution complexes. Their re-examination of past bungles was often more informative than success stories. In the search for long-term patterns, material from multitudinous sources was assembled, allowed to fester, pondered, evaluated, deconstructed, rejected and revised. Every intelligence service was a paper-driven bureaucracy. Officers in MI5, the Cheka, OGPU and the NKVD commissioned reports, compiled profiles, read and reread