The Debs of Bletchley Park and Other Stories Read Free Page B

intolerable and ‘now that we have resolved to finish it, I know that you will
all play your part with calmness and courage’. There would be ‘days of stress and strain’ ahead but it was vital that everyone pulled together and did their job.
    Many of those listening were like Phoebe. They remembered the Great War, now forever destined to be known as the First World War, and they knew at first hand the sacrifices
they had made, the loved ones lost. That was one of the reasons Chamberlain had bent over backwards in an attempt to avoid another war. The gist of his address to the nation that quiet Sunday
morning was that Hitler had given them no choice. Britain might not want war, but it was doing the right thing. Quite unfairly, Chamberlain’s name would become a byword for appeasement of
Hitler. He was certainly not a man capable of rousing the nation in the manner of Winston Churchill, who would succeed him as Prime Minister the following May, but at the time his address was seen
as both honest and, in its own modest way, suitably inspiring. He finished with the words: ‘Now may God bless you all. May he defend the right. It is the evil things that we shall be fighting
against – brute force, bad faith, injustice, oppression and persecution – and against them I am certain that the right will prevail.’
    Britain was at war but it remained far from clear what the codebreakers’ contribution might be. Dilly Knox still hadn’t broken the German Enigma codes, although he was now very close
to success, thanks to the Poles.
    The Enigma cipher machine had been invented by a German company in the early 1920s, originally for use by banks and other commercial organisations that needed to keep data
confidential. It was adopted by the German Navy in 1926 and two years later by the German Army. The machine itself looked rather like a typewriter encasedin a wooden box. It
had a keyboard and on top of the machine was a lampboard with a series of lights, one for every letter, laid out in the same order as the keyboard. The main internal mechanism was made up of three
metal rotors, each with twenty-six electrical contacts around its circumference, one for every letter of the alphabet.
    In order to encode the message, the operator set the rotors in a predetermined order and position, known as the settings. He then typed each letter of the message into the machine. The action of
pressing the key sent an electrical impulse through the machine which passed through each of the rotors and lit up the encoded letter on the lampboard.
    The machine didn’t print anything out and it didn’t send the message itself. The operator simply noted down the encoded letter from the lampboard and typed in each of the other
letters until he had a completely encoded message which he sent via wireless, normally using Morse code.
    As a letter was typed in the first rotor moved forward one position. After that rotor had moved a certain number of times, the second rotor moved forward once, and after the second rotor had
moved a number of times, the third rotor moved once. As a result, the code was constantly changing with every letter. The Germans added a plugboard providing an additional level of security which
they believed made Enigma unbreakable.
    But they were wrong. The Poles, who shared a border with the Germans and had never stopped seeing them as a threat, had begun trying to break Enigma shortly after the Germans first started using
it. The Polish codebreakingorganisation, the
Bureau Szyfrow,
employed a group of mathematicians led by a young man called Marian Rejewski, who used mathematics to
work out the internal wiring and mechanism of the German Army Enigma machine. He was helped by a spy inside the German War Ministry, an army colonel who provided the French with the Enigma settings
and operations manual in return for money and sex; the French shared this intelligence windfall with the Poles. It certainly gave the Polish