GCHQ. Richard Aldrich

in the Middle East.¹⁴

      Scott-Farnie gave the Soviets a good deal of information on low-grade German Air Force systems, but quickly came up against a different culture of intelligence exchange.¹⁵ The Soviets adored captured documents, and did not attach much credence to any information that was not supported by such evidence. Once the game of document exchange began, Scott-Farnie discovered that the Soviet approach ‘was precisely that of a horse dealer who enjoys the poste and riposte of a bargain, and they looked at the exchange of documents on an eye for an eye basis’.¹⁶

      Bletchley now had to decide whether to follow up the Scott-Farnie Mission. Alastair Denniston was ‘full of hesitation because of the continued Soviet retreat before the German onslaught’, but the intelligence directorates of Britain’s three armed services thought it worthwhile. Josh Cooper, who had reviewed the exchanged material, concluded that the Soviets were ‘absolute beginners’ in their work on the German Air Force, but thought they should be shown the RAF Y stations at Kingsdown in Kent and Cheadle in Cheshire to point them in the right direction. If the Soviets were impressed, he added, they might allow a British Y unit to be sent to the Soviet Union.¹⁷ In the end, Edward Crankshaw, an Army Y Service officer, was sent out, armed with more barter material in the form of documents. This was to be ‘swapped’ with the Soviet interceptors, since Bletchley Park thought ‘there is no better analogy than the schoolboy with his stamp collection’. By the spring of 1942 Crankshaw was established in the Soviet Union, and was trading his wares.¹⁸ However, the greatest success in the Soviet Union was achieved by the Royal Navy. It was running supply convoys to the Russian port of Murmansk, and this justified the setting up of a radio station at the nearby town of Polyarnoe. A small naval Y intercept party was soon attached to it, and began cooperating with the Soviets on low-level German naval communications. This kept going until December 1944, and yielded good material on subjects such as the movements of the German battleship Tirpitz in northern waters.¹⁹

      The main worry about giving Ultra to the Soviets was the insecurity of their own cyphers – in 1942, Bletchley Park was increasingly aware of the German ability to read a great deal of Soviet operational military traffic in the field. Frederick Winterbotham, who worked on sigint distribution, argued that Moscow simply had to be told about the weak security of its cyphers. However, Winterbotham’s colleagues insisted that it was ‘impossible’ to tell the Soviets, even though he had ‘invented a good cover story’ to explain how they knew.²⁰ The secret truth was that Bletchley Park was collecting second-hand sigint. The Germans were sending their own sigint from the Eastern Front back to Berlin using an Enigma key code-named ‘Mustard’, which in turn was being read by the British. Although much of the sigint obtained from the Soviets was operational, the British also noted that ‘first grade traffic can be read – at least in part’ by the Germans. Some of the German successes had stemmed from a Soviet codebook, ‘OKK–5’, known to have been captured by the Finns and given to the Germans. While the British had struggled to break these codes in the 1930s, the Germans were having more success.²¹ On 16 June 1942, Nigel de Grey, the Deputy Director at Bletchley Park, stepped in and settled the argument. He noted that Edward Crankshaw, the GC&CS liaison with the Soviets, would soon be returning from Moscow for another visit. He would be ordered to give the Soviets the details of their compromised cyphers and ‘the methods of reading’. This decision probably reflected the fact that, against all predictions, the Soviet forces were hanging on impressively and looked as if they were going to be in the war for some time to come.²²

      In August 1942, Crankshaw briefed the Soviets on their appalling lack of security, typified by their alarming tendency to use low-grade cyphers for high-grade secrets.²³ There was abundant evidence of this in German Air Force Enigma, but Crankshaw only hinted at it by ‘somewhat tenuous means’. Predictably, the Soviets would not accept his warnings because ‘direct evidence was not forthcoming’. Depressed, he went back to Bletchley Park in February 1943, never to return to Moscow. He joined the staff at Bletchley Park and tried to keep the relationship going at a distance, ‘but the temperature was falling’. The Director, Commander Edward Travis, was only willing to allow the relationship to continue ‘if it is a solid gain for us’. The Polyarnoe naval listening station continued to function, but with the Soviets turning the tide on the Eastern Front they seemed to feel no need for further cooperation, and other contacts ‘petered out’.²⁴ On 9 February 1944, London discussed the possibility of a visit to Britain by Soviet cypher experts and decided against it.²⁵

      Bletchley Park’s heated debate on what information to give to the Soviets was academic. All along, one of the KGB’s top agents, John Cairncross, had been working at Bletchley. Although Cairncross studied at Cambridge in the early 1930s, he was not recruited by Anthony Blunt, one of the key KGB talent scouts there, who found him both quarrelsome and arrogant. Instead, after Cairncross joined the Foreign Office in 1936, he was persuaded to work for Soviet intelligence by James Klugman, a prominent British Communist, who later served in the wartime Special Operations Executive. Although Cairncross was fearsomely intelligent, his difficult personality ensured that he was always being moved on. At the outbreak of the war with Germany he was sent to the Cabinet Office to work for the Cabinet Secretary, Lord Hankey. There he saw some of the early British thinking on the development of the atomic bomb. In 1941 he was moved to Bletchley Park, labouring in Hut Three on the Luftwaffe order of battle. His moment of triumph came in early 1943 when he was able to warn his KGB controller of the impending German armoured offensive at Kursk. Code-named ‘Operation Citadel’, this was the last great German push on the Eastern Front. It proved to be the largest tank battle of the Second World War, and the information provided by Cairncross proved to be important in launching an early attack upon the German tactical air force, much of which was destroyed on the ground. Stalin later awarded him the Order of the Red Banner in recognition of his achievement.²⁶

      Soon after Kursk, Cairncross moved again. He now returned to London and ended up in Section V, the counter-intelligence section of SIS, working alongside Kim Philby. Although he worked with Philby, Guy Burgess and indeed Donald Maclean, Cairncross was unaware of their common allegiance to Moscow, and believed he was the sole high-grade KGB agent in Whitehall. Bizarrely, he was caught in 1951 because of an official note in his handwriting found in the flat of Guy Burgess after Burgess had fled to Moscow with Maclean. Cairncross had given Burgess this quite innocently in the course of official business, without knowing he was a fellow spy. Once the note was found, Cairncross was followed, and MI5 surveillance believed they had caught him trying to meet with his KGB controller. Without hard evidence he could not be prosecuted, and he was merely asked to resign. Ironically, the Ultra material that Cairncross passed to the KGB was taken more seriously by Moscow precisely because it was stolen. Had the British handed it willingly to their ally, Stalin’s suspicious mind would almost certainly have devalued it.²⁷

      Cairncross was not the only KGB agent with access to Ultra. In late 1942, Anthony Blunt, another high-grade Soviet agent, was designated one of the two MI5 liaison officers who worked closely with Bletchley Park.²⁸ Anxiety about KGB agents and subversion was yet another reason that the British kept working on Soviet traffic. Monitoring stations, notably the Metropolitan Police intercept station at Denmark Hill in south London, reported an upswing in traffic between Moscow and secret agents in Britain. There was also a British field unit, called the Radio Security Service, that hunted for illegal agent radio transmissions, and it told the same story, although the agent traffic could not be broken.