Currier described landing at Sheerness dockyard on the afternoon of 8 February, and being met by a small delegation from Bletchley Park which included Tiltman. The crates containing the precious Top Secret ‘packages’ were loaded onto lorries and the convoy headed west towards London en route for Bletchley.
It soon became dark and the countryside was pitch black with rarely a light showing except for the faint glow emanating from a small hole scraped in the blacked-out headlight lens of the cars. When we arrived at BP, the large brick mansion was barely visible; not a glimmer of light showed through the blackout curtains. We were led through the main doors, and after passing through a blacked-out vestibule, into a dimly lit hallway, then into the office of Commander Denniston RN, chief of GC&CS. Denniston and his senior staff were standing in a semi-circle around his desk and we were introduced to and greeted by each in turn. It was truly a memorable moment for me.
Barbara Abernethy served each of the American guests with a glass of sherry. ‘It came from the Army & Navy Stores and was in a great big cask which I could hardly lift,’ she said.
But Denniston rang the bell and I struggled in and somehow managed to pour glasses of sherry for these poor Americans, who I kept looking at. I’d never seen Americans before, except in the films. I just plied them with sherry. I hadn’t the faintest idea what they were doing there, I wasn’t told. But it was very exciting and hushed voices. I couldn’t hear anything of what was said but I was told not to tell anybody about it. I guess it wasn’t general knowledge that the Americans had got any liaison with Bletchley. It was before Pearl Harbor, you see, and presumably Roosevelt was not telling everybody there was going to be any liaison at that stage.
The British kept to the precise letter of the agreement, providing detailed information on how they had broken the Enigma cypher and on their work on a number of other codes and cyphers, including Tiltman’s studies of the main Japanese Army system. But in line with the Washington discussions, no details were provided of any of the actual messages they had intercepted. Even if this had not been an American condition, it seems likely that the British would have raised it since they were concerned over the Americans’ lack of a secure system for the dissemination of the ‘Special Intelligence’.
Denniston told Menzies that Currier and his colleagues had been ‘informed of the progress made on the Enigma machine’. The Americans were given ‘a paper model of the Enigma machine, detailing its internal wiring and how it worked, together with details of the Bombes. This was as much as, if not more than, the Americans provided.
Without a shadow of a doubt, the most significant contribution on the American side had been the ability to break Purple, provided generously from the outset by the US Army codebreakers. The British were again able to read all of the ‘State Secret’ communiques passing between the main Japanese embassies and Tokyo, and in particular Oshima’s reports from Berlin on the intentions of the Nazi leadership and the German High Command.
Safford complained at what the Americans received in return, horrifying the British, and doing nothing to assuage their concerns over US security, by writing an unclassified letter to demand that the Americans be given an Enigma Machine. Safford later claimed that the British reneged on their side of the deal and had ‘double-crossed us’.
The US Navy sent the British all the Comint [communications intelligence] it had on the Japanese Navy in early 1941 and got nothing in return. For several months, US Navy personnel thought they had been double-crossed by the British and were reluctant to go ahead with collaboration in direction-finding and other matters which were greatly to England’s advantage throughout 1941. The US Army got German and Italian diplomatic systems from the British and were very happy with the deal.
The false perception that the British were holding back on the exchange deal, largely the result of the US Navy codebreakers, failure to understand the ‘paper Enigma machine’ the British had handed over, was to become endemic among a number of senior US Navy officers. Yet at the cutting edge, US codebreakers said there was nothing the British held back. Currier recalled an atmosphere of ‘complete cooperation’ and said the members of the American delegation were shown everything they wanted to see.
All of us were permitted to come and go freely and to visit and talk with anyone in any area that interested us. We watched the entire operation and had all the techniques explained in great detail. We were thoroughly briefed on the latest techniques applied to the solution of Enigma and in the operation of the Bombes. We had ample opportunity to take as many notes as we wanted and to watch first hand all operations involved. Furnishings were sparse: a desk with a chair for each of us, a pad of paper and a few pencils. The rooms were a bit cold and uncarpeted and a bit dusty but we soon found out that this was a condition common to all work spaces, including the Director’s.
The British codebreakers also did everything they could to make the Americans feel at home, Currier recalled.
During lunch hour on one of the many days at BP, we were introduced to ‘rounders’, a game resembling baseball played with a broomstick and a tennis ball. It was a relatively simple game with few complicated rules; just hit and run and deep running. It was not long before I could hit ‘home runs’ almost at will and soon wore myself out running around the bases. Many of our evenings were spent at the home of one or another of our British colleagues. Food and liquor were both rationed, especially liquor, and it was not easy for them to entertain. Whisky and gin were generally unavailable in the pubs and most people had to be satisfied with sherry.
The Americans were also taken to a number of intercept sites and to London where they were put up in the Savoy and introduced to Menzies, Currier said.
I remember standing in a doorway while a few bombs went off, none close, and walking up a narrow stairway to a little reception room with comfortable chairs and a fireplace in which a coal fire was burning. We were served tea and talked briefly about our mission. I was not clear at the time just what role the head of the British Secret Intelligence Service played in the Sigint business nor precisely why we were talking to him. I recall having the impression that he thought we knew a lot more than we did since he spent some time telling us of the difficulty of running agents and collecting intelligence from enemy territory.
We were taken by one of the Royal Navy officers to the Cafe de Paris, an underground London night club on Leicester Square. It was a favourite with Londoners for the very reason that it was underground and relatively safe during a bombing raid. On the evening we were there it was very crowded and noisy, filled with men in uniform dancing to the music of ‘Snake Hips’ Johnson, a West Indian band leader. The only thing I remember particularly about that evening is a tricycle race across the dance floor between the actor David Niven and some of his fellow officers. The following night, a delayed action bomb crashed through the four or five floors of the building over the club and exploded on the dance floor, killing most of the dancers together with ‘Snake Hips’ and his band.
Despite subsequent claims that the mission was not as successful as the Americans had hoped, the only real threat to transatlantic cooperation appears to have come during a visit to the Marconi factory at Chelmsford in Essex. ‘We were stopped at a road block in a small village,’ Currier recalled.
When the local constable saw two men in civilian clothes, obviously not British, riding in a War Department staff car, he reacted quickly and asked if we would ‘mind getting out and accompanying him to the police station’. This infuriated our diminutive Scottish driver, who jumped out and confronted the policeman: ‘Ye can nae do this, they’re Americans on a secret mission.’ This had no discernible effect on the constable and it took us the better part of an hour to convince our captors it was alright to let us proceed.
Joe Eachus, a young US naval lieutenant, was sent to Bletchley in early 1942 by Op-20-G, the US naval codebreaking unit, to find out more about the British codebreakers and what they were doing. ‘My nominal task
was to tell Washington what was happening at Bletchley Park,’ he said. ‘In that role I got around to see more of Bletchley Park than a lot of the people who were part of it.’ There was continuing mistrust on both sides. ‘As a liaison officer I was occasionally asked to get specific stuff and on one occasion I was asked by Washington for an organisational chart of Bletchley Park,’ Eachus said. ‘I went to the man in charge and said could I have a chart of the organisation. He paused and said, “I don’t believe we have one.” I didn’t pursue this with him, but I was never quite certain whether he meant we don’t have a chart, or we don’t have an organisation.’
Eachus found that the fact that he had his own rations and was happy to share them with the British helped to ease the mistrust. Although there were only two US naval officers, they were officially designated as ‘a detached unit’ and entitled to their own supplies, Joe Eachus recalled. ‘A detached unit covers a multitude of sins, from an individual to a ship,’ he said. ‘So when I went to London I got my supplies from the same place that ships did, sugar in one hundred pound bags and coffee in twenty-five pound cans. So my office was always very well supplied with sugar. Consequently when I would go to some other office to ask them to tell me about what they were doing, I would take a cup of sugar with me, which made me a good deal more welcome than I might otherwise have been.’
Bletchley Park was now playing a critical role in a large number of different military operations around the world. One of the most neglected of these is the codebreakers’ role in what was by any measure one of the most successful intelligence operations in history. The Double Cross System originated with a suggestion at the start of the war by a young MI5 officer, Dick White, that captured German agents should be ‘turned’ to work as double agents for British intelligence. At this stage, the idea was simply to find out from the questions the Germans asked what they did and did not know. One of the earliest opportunities to turn a German agent came at the start of the war with the arrest of Arthur Owens, a former MI6 agent who did a lot of business in Germany and who claimed to have been recruited as the main agent in Britain of the German intelligence service, the Abwehr. But when MI5 intercepted his correspondence with his German controller they realised he was playing the two services off against each other. Owens agreed to work as a double agent under the covername of Snow. His controller was Lieutenant-Colonel Tommy ‘Tar’ Robertson of MI5, who was to become the effective head of the Double Cross system. Snow had been given a radio transmitter and a very primitive cypher by the Germans. This was used by MI5 to send false ‘reports’ from Snow to his German controller, and was sent to Bletchley Park for evaluation. The MI5 radio operator sending the messages noticed that the control station was working to other stations using different cyphers and the messages were sent to Bletchley for analysis. But the codebreaker who looked at them expressed ‘considerable disbelief’ that they were of any importance. Despite the codebreaker’s scepticism, the radio messages were monitored by the Radio Security Service (RSS), which employed Post Office intercept operators and a small army of volunteers, most of them radio ‘hams’, who scanned the shortwave frequencies looking for German agent traffic. Major E. W. B. Gill, now head of the RSS, and a colleague, Captain Hugh Trevor-Roper (later Lord Dacre), broke one of the cyphers in use and proved the other messages were indeed Abwehr agent traffic. This caused considerable and understandable embarrassment at Bletchley and the row over the significance of the traffic went on for some time with Trevor-Roper becoming increasingly unpopular with the professional codebreakers. Eventually, though, Bletchley had to accept that Gill and Trevor-Roper were right and a new section was set up at Bletchley, in Elmer’s School, to decypher the various messages. It was headed by Oliver Strachey and both the section and its product became known as ISOS, standing for Illicit Services Oliver Strachey, although the ‘Illicit’ was frequently and understandably rendered as ‘Intelligence’. By December 1940, Strachey had broken the main hand cypher in use on the Abwehr networks. The resultant ISOS decrypts enabled MI5 to keep track of the messages of the double agents and spot any other German spies arriving in the UK. It also meant that the agents’ reports could be designed to allow the codebreakers to follow them through the Abwehr radio networks. Hopefully, this would help them break the keys for the Enigma cypher that the German controllers were using to pass the reports on to Hamburg.
By the end of 1940, Robertson had a dozen double agents under his control. A special committee was set up to decide what information should be fed back to the Germans. It included representatives of MI5, MI6, naval, military, and air intelligence, HQ Home Forces, and the Home Defence Executive, which was in charge of civil defence. The committee was called the Double Cross Committee. It met every Wednesday in the MI5 headquarters at 58, St James’s Street, in the heart of London’s clubland. Initially, with the threat of a German invasion dominating the atmosphere in London, it was decided that the ‘intelligence’ provided by the double agents should be used to give an impression of how strong Britain’s defences were. But by the beginning of 1941, it was clear that more could be done with the double agents. They could be used to deceive the Germans, to provide them with misleading information that would give Allied forces an advantage in the field.
Much of the material passed to the Germans was ‘chicken-feed’, unimportant information that would give the Abwehr a feel that its agents were doing something and had access to real intelligence without telling them anything really harmful. But mixed among this were key pieces of specious or misleading information designed to build up a false picture of what the British were doing. While the response of the Abwehr controllers to the double agents’ reports helped the Double Cross Committee to work out where the gaps in the Germans’ knowledge lay, it did not tell them whether or not the misleading intelligence picture they were attempting to build up was believed in Berlin. The only way of finding this out was by decyphering the messages passed between the Abwehr outstations in Paris, Madrid, Lisbon and their headquarters. But these links all used the Abwehr Enigma machine, which was completely different to those used by the other German services.
Hut 6 had looked at the Abwehr Enigma early in 1941 but had not seen any way to break it so it was handed over to Knox’s research section in the Cottage behind the Mansion at Bletchley. By this stage, the changes to GC&CS introduced to process the main Enigma cyphers had left Knox feeling disconcerted and unhappy. Although Knox’s research section carried out a great deal of vital work that helped the codebreakers of Hut 6 and Hut 8, he felt sidelined and remained angry that the pre-war GC&CS was being turned into a production line by the young mathematicians that Denniston had insisted on bringing in. While the mathematicians were only interested in obtaining the keys to a cypher before moving on to the next problem, Knox was frustrated by his inability to see the decyphering process through to the end. This, combined with the effects of stomach cancer, which would eventually prove terminal, made him increasingly irascible. Lever recalled tensions between Knox and Welchman over the way in which the latter had wrested control of the codebreaking operation away from him.
Dilly was usually at loggerheads with somebody or other. He rather resented, I think, that other people were having all these operational units and felt he could have done it. But then of course he wouldn’t have been able to cope. So I think it was best as it was. Dilly was a Greek scholar and an Egyptologist, looking at papyri and hieroglyphics and things. He didn’t go in for technology at all. In fact, he absolutely turned his nose up at all these young men who were coming in from Cambridge, one of them being my husband-to-be, because he said they really didn’t know what they were doing. As far as he was concerned, it was all a question of having an imaginative approach. Of course, imagination would not have got him the whole way and he knew that.
Knox was typically tetchy when Denniston objected, on the grounds of security, to his talking to Strachey about the Abwehr radio networks.
‘Dilly spent some time over a
t the School with his friend Oliver Strachey (the brother of his good Cambridge days friend Lytton) learning about the organisation of the Abwehr,’ said Mavis Lever.
First of all the many different spy networks had to be sorted out covering Madrid, Portugal, the Balkans and Turkey to see how the ISOS hand cypher messages related to Dilly’s Abwehr Enigma messages sent on from the neutral capitals to Berlin after December 1939. It was hoped that there would be good cribs from the back cypher traffic, which Dilly studied carefully. ‘Need to know’ restrictions were strictly enforced, but it is difficult to understand why Denniston considered that Dilly had no ‘need to know’ about ISOS, which was obviously so relevant to his work.
Knox sent Denniston a furious note, typically threatening, yet again, to resign, and insisting, rightly, that he needed to see the ISOS material and any other evidence relevant to the Abwehr communications, not least for the provision of ‘cribs’, if he were to be able to break the Abwehr Enigma. He also insisted that he should be the person reporting any material to London rather than Strachey’s ISOS section of Hut 3, an illustration of how irritated he was by the way in which everything at Bletchley was becoming like an intelligence factory.
My Dear Denniston
As I think you are aware I have decided to attempt a scheme for the reconstitution of one or more outlying German enigmas. Before proceeding further in the matter there are one or two points, relevant either to the matter itself or to my examination of points of attack, on which I must press for your assurances, and failing these, for your acceptance of my resignation…
The Secrets of Station X Page 16
