Perhaps he was having a dream? But when he looked back into his sitting room, there was Logie stretched out again on the sofa, and Leveret perched uneasily on the edge of one of the chairs, his hat in his hands, like an unreliable witness waiting to go into court with an under-rehearsed story.
Of course they had brought bad news. What else could it be but bad news? The acting head of Hut 8 wouldn’t travel fifty miles across country in the deputy director’s precious bloody car just to pay a social call. They were going to sack him. ‘Sorry, old thing, but we can’t carry passengers …’ Jericho felt suddenly very tired. He massaged his forehead with the heel of his hand. The familiar headache was beginning to return, spreading up from his sinuses to the back of his eyes.
He had thought it was her. That was the joke. For about half a minute, running towards the lighted window, he had been happy. It was pitiful.
The kettle was beginning to boil. He prised open the tea caddy to find age had reduced the tea leaves to dust. Nevertheless he spooned them into the pot and tipped in the hot water.
Logie pronounced it nectar.
Afterwards they sat in silence in the semi-darkness. The only illumination was provided by the faint gleam of the desk lamp behind them and the blue glow of the fire at their feet. The gas jet hissed. From beyond the blackout curtains came a faint flurry of splashes and the mournful quacking of a duck. Logie sat on the floor, his long legs outstretched, fiddling with his pipe. Jericho slouched in one of the two easy chairs, prodding the carpet absent-mindedly with the toasting fork. Leveret had been told to stand guard outside: ‘Would you mind closing both doors, old thing? The inner door and the outer door, if you’d be so kind?’
The warm aroma of toast hung over the room. Their plates had been pushed to one side.
‘This really is most companionable,’ murmured Logie. He struck a match and the objects on the mantelpiece threw brief shadows on the damp wall. ‘Although one appreciates that one is, in a sense, fortunate to be in a place like Bletchley, given where else one might be, one does start to get rather down with the sheer drabness of it all. Don’t you find?’
‘I suppose so.’ Oh, do get on with it, thought Jericho, stabbing at a couple of crumbs. Just sack me and leave.
Logie made a contented sucking noise through his pipe, then said quietly: ‘You know, we’ve all been terribly worried about you, Tom. I do hope you haven’t felt abandoned.’
At this unexpected display of concern, Jericho was surprised and humiliated to find tears pricking at his eyes. He kept looking down at the carpet. ‘I’m afraid I made the most frightful ass of myself, Guy. The worst of it is, I can’t remember much of what happened. There’s almost a week that’s pretty well a blank.’
Logie gave a dismissive wave of his pipe. ‘You’re not the first to bust his health in that place, old thing. Did you see in The Times poor Dilly Knox died last week? They gave him a gong at the end. Nothing too fancy – CMG, I think. Insisted on receiving it at home, personally, propped up in his chair. Dead two days later. Cancer. Ghastly. And then there was Jeffreys. Remember him?’
‘He was sent back to Cambridge to recover as well.’
‘That’s the man. Whatever happened to Jeffreys?’
‘He died.’
‘Ah. Shame.’ Logie performed a bit more pipe smoker’s business, tamping down the tobacco and striking another match.
Just don’t let them put me in admin, prayed Jericho. Or Welfare. There was a man in Welfare, Claire had told him, in charge of billeting, who made the girls sit on his knee if they wanted digs with a bathroom.
‘It was Shark, wasn’t it,’ said Logie, giving him a shrewd look through a cloud of smoke, ‘that did for you?’
‘Yes. Perhaps. You could say that.’
Shark nearly did for all of us, thought Jericho.
‘But you broke it,’ pursued Logie. ‘You broke Shark.’
‘I wouldn’t put it quite like that. We broke it.’
‘No. You broke it.’ Logie twirled the spent match in his long finger. ‘You broke it. And then it broke you.’
Jericho had a sudden memory-flash of himself on a bicycle, under a starlit sky. A cold night and the cracking of ice.
‘Look,’ he said, suddenly irritated ‘d’you think we could get to the point here, Guy? I mean, tea in front of the college fire talking about old times? It’s all very pleasant, but come on –’
‘This is the point, old thing.’ Logie drew his knees up under his chin and wrapped his hands around his shins. ‘Shark, Limpet, Dolphin, Oyster, Porpoise, Winkle. The six little fishes in our aquarium, the six German naval Enigmas. And the greatest of these is Shark.’ He stared into the fire and for the first time Jericho was able to have a good look at his face, ghostly in the blue light, like a skull. The eye sockets were hollows of darkness. He looked like a man who hadn’t slept for a week. He yawned again. ‘You know, I was trying to remember, in the car coming over, who decided to call it Shark in the first place.’
‘I can’t recall,’ said Jericho. ‘I’ve an idea it was Alan. Or maybe it was me. Anyway, what the devil does it matter? It just emerged. Nobody argued. Shark was the perfect name for it. We could tell at once it was going to be a monster.’
‘And it was.’ Logie puffed on his pipe. He was starting to disappear in a bank of fumes. The cheap wartime tobacco smelled like burning hay. ‘And it is.’
Something in the way he delivered that last word – some slight hesitation – made Jericho look up sharply.
The Germans called it Triton, after the son of Poseidon, the demigod of the ocean who blew through a twisted seashell to raise the furies of the deep. ‘German humour,’ Puck had groaned when they discovered the code name, ‘German fucking humour …’ But at Bletchley they stuck to Shark. It was a tradition, and they were British and they liked their traditions. They named all the enemy’s ciphers after sea creatures. The main German naval cipher they called Dolphin. Porpoise was the Enigma key for Mediterranean surface vessels and shipping in the Black Sea. Oyster was an ‘officer only’ variation on Dolphin. Winkle was the ‘officer only’ variant of Porpoise.
And Shark? Shark was the operational cipher of the U-boats.
Shark was unique. Every other cipher was produced on a standard three-rotor Enigma machine. But Shark came out of an Enigma with a specially adapted fourth rotor which made it twenty-six times more difficult to break. Only U-boats were allowed to carry it.
It came into service on 1 February 1942 and it blacked out Bletchley almost completely.
Jericho remembered the months that followed as a prolonged nightmare. Before the advent of Shark, the cryptanalysts in Hut 8 had been able to break most U-boat transmissions within a day of interception, allowing ample time to re-route convoys around the wolf packs of German submarines. But in the ten months after the introduction of Shark they read the traffic on just three occasions, and even then it took them seventeen days each time, so that the intelligence, when it did arrive, was virtually useless, was ancient history.
To encourage them in their labours a graph was posted in the code-breakers’ hut, showing the monthly tonnages of shipping sunk by the U-boats in the North Atlantic. In January, before the blackout, the Germans destroyed forty-eight Allied ships. In February they sank seventy-three. In March, ninety-five. In May, one hundred and twenty …
‘The weight of our failure,’ said Skynner, the head of the Naval Section, in one of his portentous weekly addresses, ‘is measured in the bodies of drowned men.’
In September, ninety-five ships were sunk. In November, ninety-three …
And then came Fasson and Grazier.
Somewhere in the distance the college clock began to toll. Jericho found himself counting the chimes.
‘Are you all right, old thing? You’ve gone terribly silent.’
‘Sorry. I was just thinking. Do you remember Fasson and Grazier?’
‘Fasson and who? Sorry, I don’t think I ever met them.’
‘No. Nor did I. None of us did.’
Fasson and Grazier. He never knew their Christian names. A first lieutenant and an able-bodied seaman. Their destroyer had helped trap a U-boat, the U-459, in the eastern Mediterranean. They had depth-charged her and forced her to the surface. It was about ten o’clock at night. A rough sea, a wind blowing up. After the surviving Germans had abandoned the submarine, the two British sailors had stripped off and swum out to her, lit by searchlights. The U-boat was already low in the waves, holed in the conning tower by cannon fire, shipping water fast. They’d brought off a bundle of secret papers from the radio room, handing them to a boarding party in a boat alongside, and had just gone back for the Enigma machine itself when the U-boat suddenly went bows up and sank. They went down with her – half a mile down, the Navy man had said when he told them the story in Hut 8. ‘Let’s just hope they were dead before they bit the bottom.’
And then he’d produced the code books. This was on 24 November 1942. More than nine and a half months into the blackout.
At first glance they scarcely looked worth the cost of two men’s lives: two little pamphlets, the Short Signal Book and the Short Weather Cipher, printed in soluble ink on pink blotting paper, designed to be dropped into water by the wireless operator at the first sign of trouble. But to Bletchley they were beyond price, worth more than all the sunken treasure ever raised in history. Jericho knew them by heart even now. He closed his eyes and the symbols were still there, burned into the back of his retina.
T = Lufttemperatur in ganzen Celsius-Graden. –28C = a. –27C = b. –26C = c …
U-boats made daily weather reports: air temperature, barometric pressure, wind-speed, cloud-cover … The Short Weather Cipher book reduced that data to a half-dozen letters. Those half-dozen letters were enciphered on the Enigma. The message was then broadcast from the submarine in Morse code and picked up by the German Navy’s coastal weather stations. The weather stations used the U-boats’ data to compile meteorological reports of their own. These reports were then re-broadcast, an hour or two later, in a standard three-rotor Enigma weather cipher – a cipher Bletchley could break – for the use of every German vessel.
It was the back door into Shark.
First, you read the weather report. Then you put the weather report back into the short weather cipher. And what you were left with, by a process of logical deduction, was the text that had been fed into the four-rotor Enigma a few hours earlier. It was a perfect crib. A cryptanalyst’s dream.
But still they couldn’t break it.
Every day the code-breakers, Jericho among them, fed their possible solutions into the bombes – immense electro-mechanical computers, each the size of a walk-in wardrobe, which made a noise like a knitting machine – and waited to be told which guess was correct. And every day they received no answer. The task was simply too great. Even a message enciphered on a three-rotor enigma might take twenty-four hours to decode, as the bombes clattered their way through the billions of permutations. A four-rotor Enigma, multiplying the numbers by a factor of twenty-six, would theoretically take the best part of a month.
For three weeks Jericho worked round the clock, and when he did grab an hour or two’s sleep it was only to dream fitfully of drowning men. ‘Let’s just hope they were dead before they hit the bottom …’ His brain was beyond tiredness. It ached physically, like an overworked muscle. He began to suffer blackouts. These only lasted a matter of seconds but they were frightening enough. One moment he might be working in the Hut, bent over his slide-rule, and the next everything around him had blurred and jumped on, as if a film had slipped its sprockets in a projector. He managed to beg some Benzedrine off the camp doctor but that only made his mood swings worse, his frenzied highs followed by increasingly protracted lows.
Curiously enough, the solution, when it came, had nothing to do with mathematics, and afterwards he was to reproach himself furiously for becoming too immersed in detail. If he had not been so tired, he might have stepped back and seen it earlier.
It was a Saturday night, the second Saturday in December. At about nine o’clock Logie had sent him home. Jericho had tried to argue, but Logie had said: ‘No, you’re going to kill yourself if you go on at this rate, and that won’t be any use to anyone, old love, especially you.’ So Jericho had cycled wearily back to his digs above the pub in Shenley Church End and had crawled beneath the bedclothes. He heard last orders called downstairs, listened as the final few regulars departed and the bar was closed up. In the dead hours after midnight he lay looking at the ceiling wondering if he would ever sleep again, his mind churning like a piece of machinery he couldn’t switch off.
It had been obvious from the moment Shark had first surfaced that the only acceptable, long-term solution was to redesign the bombes to take account of the fourth rotor. But that was proving a nightmarishly slow process. If only they could somehow complete the mission Fasson and Grazier had begun so heroically and steal a Shark Enigma. That would make the redesign easier. But Shark Enigmas were the crown jewels of the German Navy. Only the U-boats had them. Only the U-boats and, of course, U-boat communication headquarters in Sainte-Assise, southeast of Paris.
A commando raid on Sainte-Assise, perhaps? A parachute drop? He played with the image for a moment and then dismissed it. Impossible. And, in any case, useless. Even if, by some miracle, they got away with a machine, the Germans would know about it, and switch to a different system of communications. Bletchley’s future rested on the Germans continuing to believe that Enigma was impregnable. Nothing could ever be done which might jeopardise that confidence.
Wait a minute.
Jericho sat upright.
Wait a bloody minute.
If only the U-boats and their controllers in Saint-Assise were allowed to have four-rotor Enigmas – and Bletchley knew for a fact that that was the case – how the hell were the coastal weather stations deciphering the U-boat’s transmissions?
It was a question no one had bothered to stop and ask, yet it was fundamental.
To read a message enciphered on a four-rotor machine you had to have a four-rotor machine.
Or did you?
If it is true, as someone once said, that genius is ‘a zigzag of lightning across the brain’, then, in that instant, Jericho knew what genius was. He saw the solution lit up like a landscape before him.
He seized his dressing gown and pulled it over his pyjamas. He grabbed his overcoat, his scarf, his socks and his boots and in less than a minute he was on his bike, wobbling down the moonlit country lane towards the Park. The stars were bright, the ground was iron-hard with frost. He felt absurdly euphoric, laughing like a madman, steering directly into the frozen puddles along the edge of the road, the ice crusts rupturing under his tyres like drum skins. Down the hill he freewheeled into Bletchley. The countryside fell away and the town spread out beneath him in the moonlight, familiarly drab and ugly but on this night beautiful, as beautiful as Prague or Paris, perched on either bank of a gleaming river of railway tracks. In the still air he could hear a train half a mile away being shunted in the sidings – the sudden, frantic chugging of a locomotive followed by a series of clanks, then a long exhalation of steam. A dog barked and set off another. He passed the church and the war memorial, braked to avoid skidding on the ice, and turned left into Wilton Avenue.
He was panting with exertion by the time he reached the Hut, fifteen minutes later, so much so he could barely blurt out his discovery and catch his breath and stop himself from laughing at the same time: ‘– They’re – using – it – as – a – three-rotor – machine – they’re – leaving – the – fourth – rotor – in – neutral – when – they – do – the – weather – stuff – the – silly – bloody – buggers –’
His arrival caused a commotion. The night shift all stopped working and gathered in a concerned half-circle round him – he remembered Logie, Kingcome, Puck and Proudfoot – and it was clear from their expressions they thought he really had
gone mad. They sat him down and gave him a mug of tea and told him to take it again, slowly, from the beginning.
He went through it once more, step by step, suddenly anxious there might be a flaw in his logic. Four-rotor Enigmas were restricted to U-boats and Sainte-Assise: correct? Correct. Therefore, coastal stations could only decipher three-rotor Enigma messages: correct? Pause. Correct. Therefore, when the U-boats sent their weather reports, the wireless operators must logically disengage the fourth rotor, probably by setting it at zero.
After that, everything happened quickly. Puck ran along the corridor to the Big Room and laid out the best of the weather cribs on one of the trestle tables. By 4 A.M. they had a menu for the bombes. By breakfast one of the bombe bays was reporting a drop and Puck ran through the canteen like a schoolboy shouting: ‘It’s out! It’s out!’
It was the stuff of legend.
At midday Logie telephoned the Admiralty and told the Submarine Tracking Room to stand by. Two hours later, they broke the Shark traffic for the previous Monday and the Teleprincesses, the gorgeous girls in the Teleprinter Room, began sending the translated decrypts down the line to London. They were indeed the crown jewels. Messages to raise the hairs on the back of your neck.
FROM: U-BOAT TO CAPTAIN SCHRÖDER
FORCED TO SUBMERGE BY DESTROYERS. NO CONTACT.
LAST POSITION OF ENEMY AT 0815 NAVAL GRID SQUARE 1849.
COURSE 45 DEGREES, SPEED 9 KNOTS.
FROM: GILADORNE
HAVE ATTACKED. CORRECT POSITION OF CONVOY IS AK1984. 050 DEGREES. AM RELOADING AND KEEPING CONTACT.
FROM: HAUSE
AT 0115 IN SQUARE 3969 ATTACKED, FLARES AND GUNFIRE, DIVED, DEPTH CHARGES. NO DAMAGE. AM IN NAVAL GRID SQUARE AJ3996. ALL TIN FISH, 70 CBM.
FROM: FLAG OFFICER, U-BOATS
TO: ‘DRAUFGÄNGER’ WOLF PACK
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