The Bletchley Park Codebreakers

by Michael Smith

  Churchill would never have tolerated the confusion allowed by Roosevelt in both the production and the distribution of Magic. He also showed far greater appreciation both of his cryptanalysts and the intelligence which they produced. Captain Malcolm Kennedy, one of the leading Japanese experts at Bletchley Park, wrote in his diary on 6 December 1941:

  … The All Highest (… Churchill) is all over himself at the moment for latest information and indications re Japan’s intentions and rings up at all hours of the day and night, except for the 4 hours in each 24 (2 to 6 a.m.) when he sleeps. For a man of his age, he has the most amazing vitality.

  It would never have occurred to Roosevelt to ring up his cryptanalysts for the latest news. (Had he done so on 6 December, he would have discovered the confusion in the decryption of the fourteen-part Japanese telegram caused by the odd-even day arrangement.) Churchill also showed far greater determination than Roosevelt to ensure that his cryptanalysts had adequate resources. The American intelligence failure to provide advance warning of the Japanese attack on Pearl Harbor was due primarily to the difficulties in reading the latest variant of the main Japanese naval code, JN-25B. Though Magic contained no clear indication of plans for the surprise attack, undecrypted naval messages did. ‘If the Japanese navy messages had enjoyed a higher priority and [had been] assigned more analytic resources,’ writes the official historian of the NSA (the current US Sigint agency), Frederick Parker, ‘could the U. S. Navy have predicted the Japanese attack on Pearl Harbor? Most emphatically yes!’ JN-25B was not read to any great extent before Pearl Harbor because only a total of between two and five cryptanalysts had ever been assigned to work on it. The success in breaking Japanese naval codes, when the number of cryptanalysts was increased after Pearl Harbor, was a crucial element in the US victory at Midway only six months later.

  In the months before Pearl Harbor, when OP-20-G lacked the resources required to read JN-25B more fully, it did not occur to American naval cryptanalysts to appeal directly to Roosevelt. At exactly the same time, faced with a less critical though still serious shortage of resources, Bletchley Park’s leading cryptanalysts appealed directly to Churchill. The most junior of them, Stuart Milner-Barry, delivered the message personally to Number 10. Churchill’s response was immediate: ‘ACTION THIS DAY. Make sure they have all they want on extreme priority and report to me that this has been done.’

  2

  THE GOVERNMENT CODE AND CYPHER SCHOOL AND THE FIRST COLD WAR

  MICHAEL SMITH

  Introduction

  Our view of espionage is now so dominated by the period known as the Cold War, that it is easy to forget that between the First and Second World Wars, Britain and the Soviet Union fought a first Cold War every bit as bitter as the second. The predecessors of the KGB regarded Britain as ‘the main adversary’ and there were widespread attempts to collect intelligence, to subvert British society, and to recruit agents within the British establishment, of whom the members of the Cambridge spy ring were only the most prominent. The following chapter traces the early beginnings of GC&CS and examines the part played by the British codebreakers in this first Cold War. It also dismantles the myth that once the Germans turned on the Russians - in June 1941 - the British stopped collecting intelligence on their newfound Soviet allies. Although their armies were united in the ‘hot war’ against Germany, the intelligence services on both sides would very soon be positioning themselves to fight the new Cold War that would follow the victory over the Nazis.

  MS

  Britain’s codebreakers enjoyed a very successful First World War. Perhaps the best known of their achievements was the breaking, by the Royal Navy’s Room 40, of the Zimmermann Telegram, which brought the United States into the war. But even before Room 40 was created, on the orders of the then First Lord of the Admiralty, Winston Churchill, the Army’s MI1b had achieved considerable success against German military codes and ciphers.

  The Army and Navy codebreaking units rarely spoke to each other, engaging in a turf war apparently fuelled by the Army’s resentment of the greater influence of the upstart in the Admiralty. Alastair Denniston, who for much of the war led Room 40, or NID25, as it was more correctly known, later bemoaned ‘the loss of efficiency to both departments caused originally by mere official jealousy’. The two departments finally began to exchange results in 1917, but there remained little love lost and the situation came to a head a year after the Armistice, when the question of whether or not there should be a peacetime codebreaking organization was under consideration.

  Although there were inevitably some within government who were keen to axe the codebreakers as part of a peace dividend, there were many more who were just as eager to continue to receive the intelligence they were providing. It was decided to amalgamate the two organizations and a conference was held at the Admiralty in August 1919 to consider who should be in charge of the new body. The War Office wanted their man. Major Malcolm Hay, the head of MI1b, while the Navy was equally determined that Denniston was the worthier candidate.

  But Hay appears to have overplayed his hand, insisting he was not prepared to work under Denniston, while the latter expressed a willingness to do whatever was asked of him. The generals were embarrassed by Hay’s attitude. It was not for junior officers to decide who they were or were not prepared to serve under. Denniston was subsequently given charge of what was to be known as the Government Code and Cypher School (GC&CS), with a staff of just over fifty employees, of whom only a half were codebreakers. ‘The public function was “to advise as to the security of codes and cyphers used by all Government departments and to assist in their provision”,’ Denniston later recalled. ‘The secret directive was “to study the methods of cypher communications used by foreign powers”.’

  GC&CS came under the control of the Director of Naval Intelligence, Admiral Hugh ‘Quex’ Sinclair, a noted bon viveur who installed the School in London’s fashionable Strand, close to the Savoy Grill, his favourite restaurant. The material it dealt with was almost entirely diplomatic traffic. Its main target countries were America, France, Japan and Russia, with the last providing what Denniston said was ‘the only real operational intelligence’.

  ‘The Revolutionary Government in 1919 had no codes and did not risk using the Tsarist codes, which they must have inherited,’ Denniston said. ‘They began with simple transposition of plain Russian and gradually developed systems of increasing difficulty.’ One of the reasons that the Bolsheviks were unwilling to use the old Tsarist codes was the presence among the British codebreakers of the man responsible for devising a number of them. Ernst Fetterlein had once been the Tsar’s leading code-breaker, solving not just German and Austrian codes but also those of the British.

  ‘Fetterlein was a devotee of his art,’ one of his former colleagues in the Russian Cabinet Noir recalled. ‘I was told that once, when he was sent to London with dispatches, he sat morosely through breakfast until suddenly a complete change took place. He beamed, began to laugh and jest, and when one of the embassy officials asked him what the matter was, confessed that he had been worried by an indecipherable word which occurred in one of the English telegrams he had deciphered. Someone had in conversation mentioned the name of a small English castle to which the King had gone to shoot and this was the word in the telegrams which had bothered him.’ He sported a large ruby ring given to him by Tsar Nicholas in gratitude for his achievements, which included deciphering a message that led to the sinking of a number of German ships in the Baltic in 1914. This had a valuable spin-off for Fetterlein’s future employers. The Russians recovered a naval codebook from the light cruiser the Magdeburg, which they passed on to the British.

  Fetterlein fled from Russia during the October Revolution on board a Swedish ship. He and his wife narrowly evaded a search of the ship by the Russians, one of his new colleagues recalled him saying. ‘As the top cryptographer in Russia he held the rank of admiral and his stories of the day the revolution occurred, when workmen s
tripped him of many decorations and bullets narrowly missed him, were exciting. It is said that the French and the British organisation were anxious to get him and Fetterlein simply sat there and said: “Well gentlemen, who will pay me the most?”’

  The British evidently offered the most money. Fetterlein was recruited by Room 40 in June 1918, working on Bolshevik, Georgian and Austrian codes. ‘Fetty, as we addressed him, would arrive precisely at 9.30 and read his Times until 10 when he would adjust a pair of thick-lensed glasses and look to us expecting work to be given to him. He was a brilliant cryptographer. On book cipher and anything where insight was vital he was quite the best. He was a fine linguist and he would usually get an answer no matter the language.’

  Fetterlein and his team, who included two female refugees from Russia and the occasional British Consul thrown out by the Bolsheviks, were easily able to keep on top of the relatively simple Bolshevik ciphers. This allowed them to ensure that the government of David Lloyd George was fully informed of the machinations of various elements of the Russian Trade Delegation, led by the Bolshevik Commissar for Foreign Trade, Leonid Krasin, which arrived in London in May 1920.

  The messages decrypted by GC&CS were known as BJs because they were circulated in blue-jacketed files, as opposed to the red files used for reports from the Secret Intelligence Service (SIS), now better known as MI6. The Russian BJs showed Lenin telling Krasin that he must be tough with the British. ‘That swine Lloyd George has no scruples or shame in the way he deceives,’ said the Soviet leader. ‘Don’t believe a word he says and gull him three times as much.’ Lev Kamenev, the head of the Moscow Communist Party, was sent to London to take charge of the delegation. Very soon the decrypts showed that he was actively involved in the setting up of ‘Councils of Action’ across Britain, with the intention of using them, like the Russian Soviets, to prepare for a communist revolution in Britain. They also disclosed that the Russians were pouring money into the London-based Daily Herald newspaper.

  To many of those in authority, it appeared that Britain was perilously close to its own communist insurrection. Field Marshal Sir Henry Wilson, the Chief of the Imperial General Staff, wrote a furious memorandum to Lloyd George. The telegrams showed ‘beyond all possibility of doubt … that Kamenev and Krasin, while enjoying the hospitality of England, are engaged, with the Soviet Government, in a plot to create red revolution and ruin this country’. He received support from Admiral Sinclair, who surprisingly urged the Government to publish the decrypted telegrams. ‘Even if the publication of the telegrams was to result in not another message being decoded, then the present situation would fully justify it,’ claimed Sinclair.

  Lloyd George then sanctioned the publication of eight of the telegrams as long as the newspapers claimed to have obtained them from ‘a neutral country’. But The Times ignored the official requests to keep the true source secret, starting its report with the words: ‘The following telegrams have been intercepted by the British Government.’ The Prime Minister called in Kamenev, who was due to return to Russia for consultations and told him there was ‘irrefutable evidence’ that he had committed ‘a gross breach of faith’. He would not be allowed back into the country.

  Despite the Times report, and further press leaks after Kamenev’s departure, the Russians did not change their ciphers. There was no doubt that they were aware of what had happened. Krasin told Maxim Litvinov, the Bolshevik Deputy Commissioner for Foreign Affairs, that the British ‘had complete knowledge of all your ciphered telegrams … which had strengthened the suspicion that Kamenev is the teacher of revolutionary Marxism and was sent here with the express purpose of inspiring, organizing and subsidizing English Soviets’.

  But the Russian ciphers were still not changed until three months later, when Mikhail Frunze, Commander-in-Chief of the Bolshevik forces fighting the White Russians in the Crimea, reported that ‘absolutely all our ciphers are being deciphered by the enemy in consequence of their simplicity’. He singled out the British as one of the main perpetrators. ‘All our enemies, particularly England, have all this time been entirely in the know about our internal military operational and diplomatic work,’ he added. A week later, the trade delegation in London was told to send correspondence by courier until they received new ciphers. They arrived in January 1921 and by April, Fetterlein had broken them.

  The main source of the coded messages coming into GC&CS was the international cable companies. Under a section added to the 1920 Official Secrets Act, they were obliged to hand over any cables passing through the United Kingdom – a requirement that was quite openly put down to the ‘general state of world unrest’ created by communist attempts to replicate the October Revolution across Europe. But many of the messages emanating from Moscow were intercepted by Royal Naval intercept sites – based at Pembroke and Scarborough – and Army sites at Chatham, Baghdad and Constantinople. Although GC&CS remained under Admiralty control, the vast bulk of the messages it decrypted were now diplomatic rather than military or naval and in 1922, Lord Curzon, the Foreign Secretary, decided that the Foreign Office should take charge of the codebreakers. One senior member of staff attributed this to a conversation with the French ambassador during which the Foreign Secretary ‘expressed certain views which did not coincide with the views of his colleagues in the cabinet’. These were duly passed back to Paris, decrypted by GC&CS and circulated among Curzon’s cabinet colleagues. The codebreakers were moved from their Strand headquarters to 178 Queen’s Gate and a year later again put under the control of Admiral Sinclair, who was now the Chief of MI6.

  Despite his interest in the codebreakers’ intelligence product, Curzon showed little regard for its security. When further evidence of the Russian attempts to subvert Britain and its empire emerged in 1923, he used the deciphered telegrams to draft a protest note to the Soviet Government – the so-called Curzon ultimatum – which not only quoted the telegrams verbatim but made absolutely clear that they were intercepts, most of them passing between Moscow and its envoy in Kabul. These were almost certainly intercepted, and probably deciphered, in India where there was a well-established signals intelligence operation.

  One of the leading cryptographers in India at the time was Captain John Tiltman, who was undoubtedly one of the best codebreakers in Britain, if not the world. He had been offered a place at Oxford at the age of thirteen but had been unable to accept. He subsequently served with the King’s Own Scottish Borderers in France during the First World War, where he won the Military Cross, and spent a year with GC&CS before being posted to the Indian Army headquarters at Simla in 1921. There was already a military intercept site at Pishin on the Baluchistan-Afghan border and Tiltman’s arrival coincided with the opening of another intercept station at Cherat, on the North West Frontier.

  Tiltman later recalled that he was part of a small section of no more than five people based at Simla. It not only deciphered the messages, but also garnered intelligence from the locations of the transmitters – which were determined by direction finding – from the way they operated, and from the routine communications, a process still known today as traffic analysis. ‘We were employed almost entirely on one task, to read as currently as possible the Russian diplomatic cipher traffic between Moscow, Kabul in Afghanistan and Tashkent in Turkestan,’ he said. ‘From about 1925 onwards, I found myself very frequently involved in all aspects of the work – directing the interception and encouraging the operators at our intercept stations on the North West Frontier of India, doing all the rudimentary traffic analysis that was necessary, diagnosing the cipher systems when the frequent changes occurred, stripping the long additive keys, recovering the codebooks, translating the messages and arguing their significance with the Intelligence Branch of the General Staff. I realize that I was exceptionally lucky to have this opportunity and that very few others have had the chance of acquiring this kind of general working experience. Between 1921 and 1924, I paid three visits to the corresponding unit in Baghdad and on several oc
casions, sitting amongst operators in the set-room of the Baghdad intercept station, worked directly on the red forms fresh off the sets, to the benefit not only of my own experience but also to the morale of the operators.’

  The Indian signals intelligence operation, which was regarded as part of Sinclair’s overall organization, took any Russian traffic it could, including the communications of the OGPU, forerunner of the KGB. It achieved ‘very considerable cryptographic success’, according to one military official. A Wireless Experimental Station was opened at Abbottabad on the North West Frontier with a further intercept site at Quetta. Meanwhile, the site in Constantinople was withdrawn to Sarafand, near Jaffa, in Palestine, as No. 1 section of 2 Wireless Company, with Baghdad forming No. 2 section. Like the Indian operation, Sarafand had its own cryptographers, producing intelligence for the British Middle East Command. It also sent raw Russian traffic back to London where it was passed on to GC&CS, considerably increasing the amount of Russian traffic available to Fetterlein and his assistants.

  The increased amount of traffic coincided with yet another change in the Soviet ciphers, leading to calls for more Russian experts. One of those recruited as a result was J. E. S. ‘Josh’ Cooper, who was to become another leading light at Bletchley Park. He heard of the openings at GC&CS through a friend, the novelist Charles Morgan.

  I joined as a Junior Assistant in October 1925. Like many other recruits, I had heard of the job through a personal introduction – advertisement of posts was, at that time, unthinkable. I was one year down from University of London, King’s College, with a first in Russian and had nothing better to do than teach at a preparatory school at Margate. My father was bewailing this at tea with the Morgans one day, and one of Charles’s sisters said she had a friend who worked at a place in Queen’s Gate where Russian linguists were wanted.