Enigma

north of the Park, in a hut in a clearing in the forested estate of Gayhurst Manor, a clutch of tired Wrens near the end of their shift were being ordered to halt the three bombes running on Nuthatch (Berlin-Vienna-Belgrade Army administration), strip them and prepare them for Shark. In the stable block of Adstock Manor, ten miles to the west, the girls were actually sprawled with their feet up beside their silent machines, drinking Ovaltine and listening to Tommy Dorsey on the BBC Light Programme, when the supervisor came storming through with a sheaf of menus and told them to stir themselves, fast. And at Wavendon Manor, three miles northeast, a similar story: four bombes in a dank and windowless bunker were abruptly pulled off Osprey (the low-priority Enigma key of the Organisation Todt) and their operators told to stand by for a rush job.
    Those, plus the two machines in Bletchley's Hut 11, made up the promised dozen bombes.
    The mechanical check completed, the Wren went back to the first row of drums and began adjusting them to the combination listed on the menus. She called out the letters to the other girl, who checked them.
    'Freddy, Butter, Quagga . . .'
    'Yes.'
    'Apple, X-ray, Edward
    'Yes.'
    The drums slipped on to their spindles and were fixed into place with a loud metallic click. Each was wired to mimic the action of a single Enigma rotor: 108 in all, equivalent to thirty-six Enigma machines running in parallel. When all the drums had been set, the bombe was trundled back into place and the motor started.
    The drums began to turn, all except one in the top row which had jammed. The engineer gave it a whack with his spanner and it, too, began to revolve. The bombe would now run continuously on this menu—certainly for one day; possibly, according to Jericho's calculations, for two or three—stopping occasionally when the drums were so aligned they completed a circuit. Then the readings on the drums would be checked and tested, the machine restarted, and so it would go on until the precise combination of settings had been found, at which point the cryptanalysts would be able to read that day's Shark traffic. Such, at any rate, was the theory.
    The engineer began dragging out the other bombe and Jericho moved forward to help, but was stopped by a tugging on his arm.
    'Come on, old love,' shouted Logie above the din.
    'There's nothing more we can do here.' He pulled at his sleeve again.
    Reluctantly, Jericho turned and followed him out of the hut.
    He felt no sense of elation. Maybe tomorrow evening or maybe on Thursday, the bombes would give them the Enigma settings for the day now ending. Then the real work would begin—the laborious business of trying to reconstruct the new Short Weather Code Book—taking the meteorological data from the convoy, matching it to the weather signals already received from the surrounding U-boats, making some guesses, testing them, constructing a fresh set of cribs ... It never ended, this battle against Enigma. It was a chess tournament of a thousand rounds against a player of prodigious defensive strength, and each day the pieces went back to their original positions and the game began afresh.
    Logie, too, seemed rather flat as they walked along the asphalt path towards Hut 8.
    'I've sent the others home to their digs for some kip,' he was saying, 'which is where I'm going. And where you ought to go, too, if you're not too high to sleep.'
    I'll just clear up here for a bit, if that's all right. Take the code book back to the safe.'
    'Do that. Thanks.'
    'And then I suppose I'd better face Wigram.'
    'Ah, yes. Wigram.'
    They went into the hut. In his office, Logie tossed Jericho the keys to the Black Museum. 'And your prize,' he said, holding up a half-bottle of scotch. 'Don't let's forget that.'
    Jericho smiled. 'I thought you said Skynner was offering a full bottle.'
    'Ah, well, yes, I did, but you know Skynner.'
    'Give it to the others.'
    'Oh, don't be so bloody pious.' From the same drawer Logie produced a couple of enamel mugs. He blew away some dust and wiped their insides with his forefinger. 'What shall we drink to? You don't mind if I join you?'
    'The end of Shark? The future?'
    Logie splashed a large measure of whisky into each mug. 'How about,' he said, shrewdly, offering one to Jericho, 'how about your future?'
    They clinked mugs.
    'My future.'
    They sat in their overcoats, in silence, drinking.
    'I'm defeated,' said Logie at last, using the desk to pull