Between Silk and Cyanide Read online

  I told Tommy that the poem-code must go and be replaced by one which the agents could not possibly remember. Their transposition keys must never again be based on words, poetic or otherwise. They must be mass-produced by hand by specially trained groups of coders shuffling numbered counters at random.

  We would give each agent a series of transposition keys already worked out for him – and printed on silk. To encode a message, he would simply have to copy out the keys we had prepared for him – and immediately cut them away from the silk and burn them. There would be no way that he could possibly remember the figures he had used. They would all have been selected at random – and would be different for every single agent in the field.

  Each silk would contain sufficient keys for two hundred messages – a hundred from the agent to us, a hundred from us to him. The greatly increased security of these ‘worked-out’ keys would allow the messages to be shorter. One hundred letters could be sent instead of the existing minimum of two hundred.

  The cryptographic parlour game would be closed for the season. Enemy cryptographers would no longer have poems to reconstruct and would have to tackle every single message individually – an undertaking which was anathema to all cryptographers. Every message to and from the field would confront them with a new code, and to sustain an ‘absolute priority’ attack on this kind of traffic would mean that the bulk of Germany’s cryptographic manpower would have to be deflected on to SOE – which would in itself be a major contribution to the war effort.

  Indecipherables would be reduced to a minimum because we would no longer have to play the guessing game, ‘Which word has he misspelt?’ The worked-out keys would also be proof against Morse mutilation, which frequently rendered perfectly encoded messages indecipherable because the indicator groups (telling us which words the agent had chosen) were so badly garbled.

  Silk itself was easy to cut, easy to burn and easy to camouflage. If the Gestapo or Vichy police ran their hands over an agent’s clothing during a random street search, silk sewn into the lining could not be detected.

  All the resources of the Gestapo would not force an agent to reveal a code he could not possibly remember. Destroying his worked-out keys as soon as he had used them must become as reflex to an agent as pulling the ripcord of his parachute.

  But there was one thing for which he could still be tortured. His security check. And this to me was the most haunting and daunting issue of all. If we couldn’t solve this problem, we had solved nothing.

  For the first time I found myself wondering how best to put something to that silent, motionless figure with his unlit cigar. ‘I need two minutes, Tommy.’

  I grabbed a sheet of paper and started scribbling. Tommy would know if what followed was right, and I would be bound by his judgement.

  When I’d finished, I wrote something on the blotter in front of me and covered it with an ashtray. I then showed him my scribbling. It was intended to be an artist’s impression of how a silk code would look. All it lacked was the artist:

  OUTSTATION TO HOME

  14.2.13.4.6.13.1.5.7.15.3.9.11.16.10.8.

  6.10.13.2.4.11.7.9.12.3.5.8.1.

  CEDQT

  9.10.1.7.11.4.12.8.5.2.6.13.3.

  11.5.7.12.2.6.3.8.9.1.10.4.

  PKBDO

  2.9.5.10.14.1.6.11.4.15.8.3.12.12.7.

  4.6.1.5.7.9.2.1.13.8.12.10.

  RYTGE

  6.3.7.4.8.9.2.10.5.11.13.1.14.12.

  3.1.10.4.6.2.7.8.5.9.11.

  UVHJG

  4.7.8.1.9.2.10.11.3.5.6.12.13.14.

  4.6.7.8.5.1.9.10.2.11.12.3.

  ZAUBA

  The explanation came out in a rush and a jumble:

  ‘I’m an agent, Tommy, and I’ve been caught with my silk code on me. I’ve destroyed all the previous keys I’ve used but the Gestapo know bloody well that if they can torture my security check out of me they can use the rest of these keys to transmit messages to London and pretend they’re from me.

  ‘You’ll see that opposite each pair of keys there are five letters printed. These are indicator groups to tell London which pair of keys I’ve used to encode my message. The next pair I’m due to use are the ones at the top – starting 14.2.13.4. The indicator group is CEDQT. After this I’m due to use the next pair of keys – starting 9.10.1.7. The indicator group is PKBDO. But I never use these indicator groups exactly as they are printed. I have prearranged with London always to add 3 to the first letter and 2 to the fourth. Take the indicator CEDQT. C plus 3 is F, and Q plus 2 is S. So, instead of sending CEDQT I send FEDST. Instead of sending PKBDO I send SKBFO. At least, that’s what I’m telling you because you’re the Gestapo. All my previous indicator groups have been destroyed; how can you know if I’m telling you the truth? Rough me up and I’ll change it once again. When do you stop? Now I’ve written on this blotter what my real secret numbers are. If you can guess ’em, these Havanas are yours – and you’ll be the only cigar-smoking Kraut in Baker Street.’

  Herr Forest Frederick von Yeo-Thomas sat in silence for a very long time. I didn’t interrupt him – except to say, somewhat nervously, that this was only one of the codes I hoped to introduce.

  By the time the security-vetted cleaning women arrived to claim the office, his mind was made up. ‘You’re going to have a hell of a fight to get this accepted. I’m with you all the way. Let me know how I can help.’

  I nodded.

  ‘If it were done,’ he said, misquoting a phrase then being used as a code by an F-section agent, ‘’t were well it were done on the bloody double!’

  I agreed. The pails in the corridor sounded like church bells.

  He got up to go. Then turned by the door and looked hard at me. He must have had a strong stomach. ‘Merde alors with your new codes.’

  He then added – almost as an afterthought – ‘I may soon be needing one myself.’

  FOUR

  ‘Merde alors!’

  Scrambler telephones were in great demand in SOE because they were not only proof against crossed lines and wire-tapping but implied that those who possessed them had something to say which was worth overhearing. It hadn’t occurred to me to ask for one of my own but early in September I found that a green telephone with three buttons on it had been installed on my desk, so I must have been doing something right. Pasted across it was a memo from Dansey emphasising that it was to be used for Top Secret conversations only.

  I pressed the right buttons to tell Tommy that I had a fresh stock of Havanas, and then contacted the Grendon supervisor to ask what progress the girls were making in the task I had set them of writing poems for agents. I’d made the suggestion a fortnight ago but the girls still hadn’t produced a single stanza. Their supervisor assured me, with the hint of a chuckle, that I would not have long to wait.

  I was still pondering the significance of that chuckle when I received an incoming call on the new toy from the commanding officer of Station 53, a benign major named Phillips, who presided over his clandestine estate like a country squire.

  Dispensing with the normal courtesies, he broke some bad news in a voice so strained that I considered asking him for proof of identity. ‘Gammel’s here.’

  Brigadier Gammel was the commanding officer of the FANY Corps and I knew from a five-minute interview with her that she could cause grievous bodily harm with a glance. The whole of SOE was in awe of her. She was the embodiment of her famous pronouncement: ‘Members of the FANY Corps must at all times conduct themselves like ladies.’

  I asked the distraught major if Gammel were causing him any problems.

  ‘Almost as many as you,’ he snapped. And told me why.

  The FANY supremo had arrived at Station 53 on a tour of inspection. After examining the remotest corners of Grendon for signs of impropriety, the bellicose brigadier had walked into the FANY mess, which was normally only marginally quieter than the last few minutes of a Cup Final. But today the acute Gammel ear was greeted by absolute silence. Even more unexpected to the pie
rcing Gammel eye was the spectacle of a dozen or so FANYs clustered round a table totally absorbed in the ladylike pursuit of composing poems. She asked Phillips who had thought of this admirable idea. Mr Marks of Baker Street was given due credit. Gammel then advanced to the table to inspect the quality of her charges’ writings.

  She was now on the telephone complaining to Ozanne. Those dear girls, who knew damn well that Gammel was visiting them, had produced samples of hard-core pornography which Marks & Co. would have hidden in a glass case on the fourth floor, surrounded by Bibles.

  Phillips read to me the first (and mildest) of the stanzas Gammel had examined:

  Is de Gaulle’s prick

  Twelve inches thick

  Can it rise

  To the size

  Of a proud flagpole

  And does the sun shine

  From his arsehole?

  He invited my comments.

  I told him that the imagery was unusual, the words easy to memorise and the content not at all what the enemy would be expecting. I asked him to tell the girls that I was absolutely delighted with it and looked forward to receiving the rest.

  He put down the receiver.

  An hour later Ozanne sent for me and accused me of attempting to corrupt the FANY coders. It wasn’t the moment to tell him that almost overnight his open city of a poem-code had taken on a new dimension of menace.

  I’d learned from Dansey that there were soon to be operations, infiltrations and campaigns by the dozen in all the occupied territories, and that an unprecedented event was due to take place by the end of ’42: General de Gaulle had given his permission for an Anglo-Free French mission (the first of its kind) to be sent into France to prepare for the Allied landings in ’43, and ‘our Tommy’ was to be the Anglo.

  Then there was the invasion of North Africa, code name Torch, which General Eisenhower was planning for November/December ’42. SOE had somehow persuaded Ike to allow an SOE mission to accompany the invading forces with its own communications direct to London and France.

  There was also a mysterious operation into Norway referred to in whispers by its code name, Grouse. Whatever Grouse was, it was scheduled to take place any time from the end of September, which was only a few weeks away.

  All this new business was a major breakthrough for Baker Street head office but it was potentially an even bigger one for the German cryptographers. The moment they realised that our traffic was becoming important enough to warrant a full-scale blanket attack, the poem-code would provide them with a catalogue of wide-ranging war efforts at bargain prices.

  I hurried off to consult the only friend I had yet made in the Signals hierarchy.

  His name was Eric Heffer and he was our in-house expert on Ozanne. He was a civilian like myself but had been a captain in the First World War and preferred to be addressed as such. No one was quite sure exactly what his duties were. Occasionally he would leave his office in Norgeby House to wander at his leisure round Ozanne’s kingdom, having the effect upon all of us of a walking tranquilliser.

  Despite the daily crisis which surrounded him, Heffer remained permanently imperturbable. There was no known example of anyone or anything being able to hurry him. The one thing he could do with quite exceptional speed was think – a practice he recommended to me.

  Producing each syllable as if it were a cigarette he had just carefully rolled, he explained that Ozanne’s real weakness was not so much stupidity as respect for the Establishment. He simply couldn’t bring himself to question their judgement. If the Establishment had decided that chamber pots made first-class transmitters, he’d have had SOE peeing in Morse. Almost doing so myself, I asked a) what the Establishment specialised in and b) whether it had a name.

  No longer surprised by anything I didn’t know, he accelerated to a crawl which served to remind me of my progress. The Establishment was officially called SIS (Secret Intelligence Service) though old hands in SOE invariably referred to the rival organisation as ‘C’ (its Chief’s code name), and its speciality was thwarting SOE.

  C had been running the British Secret Service (with emphasis on the Secret) since 1911 and were appalled when SOE received a mandate from Churchill in 1940 to ‘Set Europe Ablaze’. Their agents were intelligence-gatherers: ours were saboteurs, and C were convinced that the only thing they’d set ablaze was their agents’ cover. SOE was convinced that C resented any organisation which threatened its monopoly, and the mutual antipathy had the growth potential of an obsession.

  In 1941 control of SOE’s communications became a major issue. Our wireless station at Grendon was still being constructed and we were forced to allow C to handle our early traffic. The station opened in June ’42 (the month I joined SOE) and we withdrew the traffic immediately, much to C’s annoyance, as they could no longer monitor it.

  Painstakingly Heffer finally turned to the subject which most concerned me. To C, giving codes to their peacetime agents had been a minor problem: there were so many channels of communication open to agents that poem-codes could safely be used, and this in itself was a definition of peace. But setting up two-way wireless traffic for circuits of agents in enemy-occupied territories was a wholly new event for which there were no precedents or guidelines, and by 1940 they had lost most of the agents they had put into Europe. This did not deter them from making a suggestion which threatened the existence of ours.

  Ozanne was advised by his friend and mentor Brigadier Gambier-Parry, C’s director of Signals, that their agents were going to continue using the poem-code (or some minor variation of it) as he had no doubt whatever that agents’ codes should be carried in their heads. This was all Ozanne needed to hear. What was good enough for the agents of the British Secret Service must be good enough for SOE’s.

  I waited for Heffer to tell me how we were going to transfer codes from aching heads to cuttable silk. But he chose this of all moments to indulge his knack of switching on silence as if it were air conditioning. The captain emerged from his trance freshly recommissioned to announce that even in wartime few battles were won by direct confrontation – and even fewer if they were fought inside SOE. He had several ideas for outflanking Ozanne but would need time to consider them. Drawing on the last of the day’s reserves, he agreed that worked-out keys (which we christened ‘WOKs’ to save breath) should be introduced as soon as possible – but there were ‘one or two other things wrong’ in the Signals directorate which had also to be put right. He recommended me to be patient for a little while longer.

  He was too exhausted to tell me the formula.

  The ‘one or two other things wrong’ were agents’ sets, signal plans and call-signs.

  A signal plan was a WT operator’s timetable and he had to adjust his life to it. He had to be beside his set at certain specified times or risk losing contact with London. If he missed a fixed schedule, he had to wait for the next. But a radio operator was usually responsible for the traffic of other agents, including his own organiser, all of whom had poem-codes but no training in wireless transmission. This multiplied the pressures on him to keep his inflexible schedules irrespective of risk.

  Call-signs identified an operator’s traffic to the Home Station and the Home Station’s traffic to him. They were the equivalent of Morse visiting cards and were an open invitation to the Gestapo’s social services.

  Signal plans, call-signs and codes were the fundamentals of clandestine communication. But the Signals directorate allowed no liaison between the officers who produced them. The Gauleiter of Signals preferred to keep us apart.

  I took a surreptitious trip to the suburbs of Signalsland and it was worth every Ozanne-fraught minute of it. Many resourceful and imaginative technicians had ideas for improving the wireless side of agents’ traffic but, apart from a few minor changes which had slipped through unnoticed, Ozanne had overruled them. I was prepared to leave if he vetoed WOKs.

  The whole of SOE was suddenly a department store preparing for the Christmas rush, but all I f
ound in my order book was an indecipherable from Einar Skinnarland. There were four messages from Colonel Wilson demanding that I break it.

  A workout with Skinnarland in our private gym would be a welcome respite from the prospect of going fifteen rounds with Ozanne. But the chronic invalid of coding had let me off lightly this time with a minor rupture of his key phrase, and I found the right truss for it in a matter of minutes. The message was written in his usual mixture of Norwegian and English, which was excellent security and the one thing Skinnarland could be relied upon to do properly.

  It was only when I spotted two words tucked away in the last line that I realised which of us was the chronic invalid. The words were ‘heavy water’.

  They had been distilled by Morse mutilation into ‘heaxy woter’.

  I wondered what heavy water was.

  There were half a dozen files in Dansey’s safe reserved for the special Skinnarland traffic which had been smuggled into Sweden and then re-routed to London by courier or diplomatic bag. I was allowed access to these files to help me break Skinnarland’s indecipherables but until now the only one I’d studied was the file which contained his early messages. I soon realised why they were locked in a safe.

  There were main-line telegrams from CD to Washington; main-line telegrams to CD from neutral Sweden (our men in Oslo were Munthe, Mitchelson and Binney); and main-line telegrams from Sweden to Wilson and from Wilson to Sweden; there was also a ten-page report from Munthe to Wilson (decoded by Dansey) and an even longer one (encoded by Dansey) from Wilson to Munthe.

  All of them were Top Secret. All of them dealt with the same subject: the heavy-water plant, the Norsk Hydro, at Rjukan.

  SOE’s Norwegian directorate had been mounting a massive intelligence-gathering operation which was astonishing in its breadth and detail: