homosexual exploits, were deliberately released by Blinker Hall to blacken Casement’s name during his trial – were not forgeries concocted by the British, as many Irish nationalists at the time and since have maintained, but were in fact genuine. The attempts by the German government to incite an anti-British ‘fifth column’ in Ireland, the ‘back door to England’, was a strategy that would be repeated by Hitler a generation later, in the Second World War.24
While the British secret state expanded rapidly during the First World War, the years after the war saw an equally quick deterioration of its resources. MI5 and SIS both had their budgets slashed, and MI5’s staff shrunk from 844 in 1918 to just twenty-five officers in 1925. It should be stressed that the dwindling resources of the British secret state after 1918 lay in sharp contrast to many states in post-war Europe, which turned to various forms of bloody authoritarian rule. In Soviet Russia, Fascist Italy and Nazi Germany, secret police forces expanded rapidly, and their leaders applied security practices forged during the First World War, such as mass registration and detention, to their populations even in times of peace. While the British government had interned at least 32,000 ‘enemy aliens’ on security grounds, largely on MI5’s advice, between 1914 and 1918, such drastic methods were taken only as wartime ‘emergency measures’ in Britain. The ‘totalitarian’ states of Nazi Germany and Soviet Russia, however, which were effectively at war all the time, and mobilised their populations along wartime lines, applied wartime security practices even while at peace. The head of Germany’s intelligence service in the First World War, Walter Nicolai, summarised this view when he wrote that for Germany to become a world power again it had to behave as though it was at ‘war in peace’, and would have to gather intelligence on all its enemies, at home and abroad. By contrast, the resources of the British secret state were cut so dramatically in the post-war years that by 1925 MI5 had a total of only twenty-four mail and telephone interceptions operating in the whole of Britain. Its staff consisted of just sixteen officers by 1929, and as MI5’s in-house history noted, its resources were so inadequate in the 1920s that its operations ‘reduced to a minimum’. Between 1919 and 1931, MI5 was relegated to investigating subversion in the British armed forces.25
Despite the dwindling of its resources, throughout the 1920s and 1930s MI5 continued to pride itself on its imperial responsibilities established during the First World War. During the interwar years the overwhelming thrust of MI5’s duties was focused on the threat posed by the Soviet Union. With hindsight, we can see that MI5 and SIS both miscalculated, and were slow to react to, the growing threat posed by Nazi Germany after Hitler came to power in 1933. That said, MI5’s focus on the Soviet Union was hardly irrational. Soon after the Bolshevik revolution in 1917, the Soviet Union became just as much of an empire as the former Russian tsarist empire which it replaced – and posed a similar threat to the British empire. Immediately upon coming to power, Lenin pledged his support for a worldwide revolution against imperialism, which he famously described as the ‘highest form of capitalism’. The threat posed by the Soviet Union to the British empire was exposed by the head of the Intelligence Bureau in Delhi, Sir David Petrie, who went on to become the Director-General of MI5 from 1941 to 1946. In the late 1920s he wrote a classified official history, Communism in India, 1924–27, the circulation of which was limited to a small number of senior British officials in London and Delhi. Petrie warned that the Soviet Union posed a double threat for the British empire, especially in India: Soviet expansion was a strategic threat along the traditional lines of the ‘Great Game’ with Russia, but it also posed a subversive threat, with Moscow supporting anti-colonial movements inside the British empire. As it turned out, Petrie’s forecast was remarkably accurate: for over seven decades following the Bolshevik seizure of power in 1917, interrupted only by the Second World War, the Soviet Union became the main supporter of anti-colonial movements in the British empire and other European colonial empires. The reality was therefore that throughout the 1920s and 1930s the British government was engaged in a low-level ‘cold war’ with the Soviet Union, long before the real Cold War set in after 1945.26
During the interwar years, Britain’s armed forces (the army, Royal Navy and RAF) all maintained intelligence departments that focused on the empire and Commonwealth. However, it was MI5 that was responsible for overall imperial security intelligence, maintaining direct contact with British intelligence authorities in India, the Delhi Intelligence Bureau (DIB), or Intelligence Bureau (IB) as it was also known, through a small London-based outfit known as Indian Political Intelligence (IPI). IPI was officially part of the India Office, which paid its budget, but from 1925 onwards it was housed in MI5’s headquarters at 25 Cromwell Road in London, opposite the Natural History Museum. The office space that MI5 rented to IPI (at rates that IPI often considered exorbitant) was by any standards pitiful: it consisted of three small, low-ceilinged, poorly-lit, dingy rooms in the attic of MI5’s headquarters. According to IPI’s head, Sir Philip Vickery (London Club: ‘East India’), these quarters were of such poor quality, with a ‘minimum amount of light and airspace’ and with half the main room ‘in darkness’, as to be almost ‘uninhabitable’. IPI was run on such a minuscule budget from the India Office that in 1926 it had only a handful of officers in London, equipped with three secretaries, one clerk and one typist, and apart from a few liaison officers in India, it had only two officers stationed elsewhere abroad, in Paris and Geneva. These few personnel formed the entire official security intelligence liaison channel between British intelligence and authorities in the subcontinent of India. Just how ill-equipped IPI was can be seen from a report in 1927: Vickery had to campaign hard for the purchase of ‘one extra hanging lamp’ for IPI’s attic office – for which the Department of Works ultimately seems to have refused to pay. When MI5 moved to its new headquarters, ‘Thames House’, Millbank, near Lambeth Bridge, IPI came with it, though its new accommodation was no better than before.27
Despite the scanty resources at its disposal, sharing an office with MI5 allowed IPI to collaborate closely with other sections of British intelligence. Throughout the 1920s and 1930s, MI5 and IPI continued to monitor the activities of Indian revolutionaries in Britain. Their main subject matter increasingly became communist agents travelling between Britain and India on behalf of the Communist International (Comintern), an underground network that Moscow had established in March 1919 to act as a vehicle to export the ‘workers revolution’ from the Soviet Union to countries abroad. MI5 and IPI’s investigations were focused on detecting agents acting as secret couriers for the Comintern, passing information between the British Communist Party and communist cells in India. The main investigative mechanism they relied on was a Home Office Warrant (HOW), which allowed for the interception of telephone and postal communications. Unlike SIS, which operated abroad and collected intelligence from foreign countries illegally, MI5 and IPI’s area of operations, domestically in Britain and also in the empire, were constrained by law in ways that did not apply to SIS. This was the case even though at the time MI5 (and IPI) did not have any powers at its disposal, either in statute or in common law, which allowed it to intercept mail. Despite existing in a shadowy legal netherworld, MI5 records reveal that it worked hard to operate hard within a legalistic framework, even if not a legal one.
In order to impose a HOW, MI5 had to apply to the Home Office, with a written explanation of why a warrant was sought, and the Home Secretary then had to sign off on it. HOWs were extremely resource intensive – hence the small number that were operating in the 1920s. The actual interception of communications was carried out by a small, secretive section of the General Post Office (GPO), known as the ‘special censor section’, whose workers had all signed the Official Secrets Act. This section’s work was laborious and far from glamorous: its office was equipped with a row of kettles, kept almost continually boiling, which were used to steam open letters, after which their contents were photographed, resealed and sent on their way. Some of these intercepted communications, still found in MI5 records today, contain information about the private lives of MI5 targets and their broader social history that cannot be found in any other archive. Telephone calls were likewise intercepted (‘tapped’) by the GPO, which employed a small team of transcribers at the main telephone exchange in Paddington, London. The team included foreign-language speakers, especially ‘White’ (anti-Bolshevik) Russian émigrés, who translated telephone conversations in Russian and other Eastern European languages. Later, MI5 and the GPO developed an innovative device, based on a modified