大象传媒

I am Mildred Joan Tulip nee Nichols, born 24th January 1913, recruited to Bletchley Park in 1942 after serving earlier as a VAD nurse (see Mildred Joan Tulip I). Here are my recollections, of being recruited by the Foreign Office, of the work I did on coded Enigma messages in Hut 6 and of life at Bletchley Park.

In my third year of war-time nursing, another telegram arrrived asking me to report to the Foreign office in London. There I was interviewed for some special work that I was not told much about - I had an English degree from Oxford but I chiefly remember them quizzing me about my family, checking I think that I wouldn't be a security risk - with my husband George in the Western desert (see Mildred Joan Tulip III) and my only brother Jim killed in the RAF (see Mildred Joan Tulip IV)I was not likely to do anything to support the Germans. They gave me a date to go to Bletchley Park but I still had very little idea of what i was in for. I travelled there by train, met six or seven others recruited at the same time and, before being taken off by bus to tour round the various places where we would be billeted, was shown an 'Enigma' coding machine.

The German High Command believed that the secrecy of messages to forces in the field was absolute: that its cipher was infallible. I think this belief lasted throughout the war.

For their cipher the Germans used this machine that Bletchley called 'Enigma'. It had a top like a typewriter, but inside there was complicated electrical wiring. Inside each machine were three 鈥渨heels鈥� that could be slotted in any order: 123, 231 etc. Each wheel had a disc in the centre which could be rotated and switched into any one of twenty-six positions, each position labelled with a letter of the alphabet. Each position had its own complicated wiring. This meant that each machine could be set up in millions of different ways. The only way to decipher messages was to find out how the machine sending them had been set up.

Very early in the war the Poles captured some of the German machines and they handed them over to us, the British. Once we had a few we could make more. Bletchley Park had a lot of Enigma machines.

Bletchley Park had listening stations on the South Coast and later in North Africa and Italy. The cipher used Morse code. Reception was not always easy. Two of our most skilled listeners were sometimes asked to man their machines twenty-four hours a day 鈥� just the two. Sometimes they were woken up to corroborate or give possible different readings. They were invaluable. I hope they were adequately rewarded.

Messages came to Bletchley Park by teleprinter. Each message had on it the frequency at which it was received, call signs if any, the date and time of origin and the number of letters. The rest of the message was in five letter groups. All the messages looked the same though they came from machines differently set up. The work of our group in Hut 6 was to allocate messages to the part of the German army that had sent them, so that if its cipher were broken the relevant messages would reach the right deciphering machine. [I say 鈥榩art鈥� of the German army because I don鈥檛 know the correct term: division? unit?]

Each part of the German army set up its own machine in a different way and the set up was changed every day at midnight. Hundreds of messages filled the air and the Germans themselves had to know which would decode on their machines. They solved this by using what Hut 6 called 鈥渄iscriminants鈥�. The first five-letter group of each message was made up of two letters chosen at random followed by three letters to denote the sender. The Germans knew what letters to look for. We had to find them out as early as possible each morning.

At midnight in one of the small rooms of Hut 6, one of my group would sit facing a blackboard with frequencies chalked round its edge. The first message of the day would be brought and she would chalk the last three letters of the first five-letter group beside the given frequency: suppose the letters to be JBR. Second, third and more messages would come and the last three of each one鈥檚 first five-letter group would be chalked beside the given frequency. But soon JBR would be repeated several times. Then the clever cipher breakers who hovered in the background would say 鈥淭hat鈥檚 RED鈥�. They would take the JBR = RED messages away. Any more with that discriminant were sorted out on arrival and sent straight to them. Meanwhile we went on looking for more discriminants.

鈥淩ED鈥� was the name given by Hut 6 to the German鈥檚 day by day operational cipher. Its messages themselves were not generally very important because they told what was actually happening, not future plans or strategy. But it was important as a way into other ciphers. In the early hours of every morning, six or seven a.m., and always before nine, a shout would come 鈥淩ED鈥檚 out鈥�.

For the German cipher was not infallible when the same message was sent from different parts of the army, with, of course, differently set up machines. Short messages in the early morning, e.g. 鈥淒as ist eine Abstimmsprache鈥� or 鈥淢orgensmeldung", would be sent by different parts on machines set up differently. [I don鈥檛 know German, so just make a shot at what I heard of these messages when decoded.]

I don鈥檛 know how 鈥淩ED鈥� was broken the first time. But once it was, Hut 6 used what we called 鈥淏OMBS鈥� 鈥� early computers 鈥� to help. Parallel messages to the new ones were found in yesterday鈥檚 or earlier broken REDs. Then the Bomb was asked, 鈥淎t what position of the machine would the five letter group in the undeciphered message give the five letter group in the already deciphered?鈥� I expect several parallels were run until one of them clicked. Then RED was 鈥渙ut鈥�. And then parallel messages were looked for in other groups so that a worthwhile question could be put to the Bombs. We were often asked to look for messages that tallied in time of origin and number of letters. Dr. Aitken, the Scottish chess champion of the time, who worked on difficult ciphers, often asked us to look out for special things.

The man who named most of the cipher groups was a biologist. He named them 鈥淪hrike鈥�, 鈥淥sprey鈥�, 鈥淲ryneck鈥�, 鈥淜ite鈥� etc. Much of RED was just chatter. But these other groups gave long-term plans and information that was very valuable to us. Army experts and other great brains built up a picture of the German army, its numbers, its armour, its distribution etc. They kept this picture up to date and could sometimes tell, even when ciphers were not broken, what was afoot: by increase of messages in any section, or change in direction of messages, etc.

Our chief means of sorting and allocating the different messages was by the discriminants. Frequency could be helpful: call signs sometimes. One group that we called 鈥淥range鈥� had distinctive call signs of OX, OZ, OYZ etc. These were easily identified, but I don鈥檛 think they were ever deciphered. This will have been done after the war, and it would be interesting to know what they were about.

We used discriminants, but there were always messages where the last three letters of the first five-letter group didn鈥檛 fit any known discriminants. Perhaps interception had been bad. With these messages frequency was our best clue. We sent them labelled 鈥淭ry Shrike鈥�, or whatever we thought most likely. Sometimes we must have judged right because the message didn鈥檛 come back. Sometimes it would come back labelled 鈥淣ot Shrike鈥�. Then we would try again. We tried to send every message to its proper destination.

When we established listening stations in North Africa and various parts of Italy, I became one of the 鈥淥verseas Party鈥�. We received and sorted traffic from these stations. Our traffic was a day later than that picked up in England but it was useful for comparison and we were often asked to look for special messages. In Italy a book of German call signs was captured. One of the most important tasks was to send the relevant call signs to our overseas stations as early as possible. The call signs changed every day. Only one of us was on duty at night to do this. It was a great responsibility. The call signs were sent with the 鈥淓mergency鈥� priority. We had to give a preamble to the message, different every day, and we had to vary the length of our messages. I often started with a Shakespeare sonnet: 鈥淪hall I compare thee to,鈥� the call signs for today are 鈥� etc. These measures were to protect our cipher. I expect we had a machine 鈥� I don鈥檛 see why we shouldn鈥檛 even have used Enigma: it was infallible if you were aware of its weaknesses.

At the end of the war some messages came in clear 鈥� i.e. in German. A friend translated one such to me. It read: 鈥淥tto von 鈥� [I can鈥檛 remember the name] salutes his mother and sisters. This is the end. Farewell.鈥�

Most of the workers at Bletchley Park were billeted in nearby towns and villages. I was at Wolverton. The billets obviously varied. The house I was in had no running water except a cold tap in the kitchen and only an outside loo. But the people were good and kind. My landlady was a very sweet woman. In the later years a hostel was built in the grounds of Bletchley Park. It looked attractive with red floors and duck egg blue walls, but the rooms were very basic. Most of the people I knew stuck to their billets. Some looked for cottages or flats which they called 鈥淒o鈥檚鈥�. They were not easily found.

Because many billets had no baths some bath-huts were built at Bletchley Park in the later years. We covered for one another and took it in turns to luxuriate in a hot bath. On one occasion a friend came running frantically to the hut to find me because I had sent off a message with the priority 鈥淓mergency鈥� without signing it. No one else could sign it, so it was passed under the bathroom door to me. I don鈥檛 remember what the message was.

We worked shifts to cover the 24 hours. Day shift was 9 a.m. to 4 or 6 p.m. We could choose between these and if we worked till six the two hours counted as overtime. Evening shift was 4 p.m. to midnight. I liked this shift because we arrived back at billets at about 1 a.m., so could get a reasonable night and also enjoy some daytime. Night shift was midnight till 9 a.m. There were special buses to transport us to and from our billets.

On each shift we had one meal in the canteen. The food was not good but we tolerated it because it was wartime. One evening there were pineapple chunks 鈥� a rare treat 鈥� set out on the counter. As my turn in the queue approached I counted them and found that I should get the last one. But the girl serving put it away under the counter, I suppose for one of her pals. I should have protested.

We had electric kettles in our work huts so that we could make ourselves drinks when we could get hold of tea or Nescafe or powdered milk. We drank out of wartime cups, made without handles.

We could take a week鈥檚 holiday every six months and one day off each week. We could save days up and by working them in with night shifts I was sometimes able to get home for a few days. At other times I went to Oxford or London. Bletchley Park went on operating of course through Christmas and New Year and it was convenient that Scottish people liked holiday at New Year whereas English liked Christmas.

People tended to keep in small friendly groups. I liked the people I worked with. Generally Welsh and Scottish people stuck together; but my particular friend from my Hut 6 group, Muriel Fraser, was a Scot.

Many of us at Bletchley Park had husbands or brothers who were fighting somewhere so there was an underlying anxiety always. Three of the people I worked with received the dreaded telegram. We shared their grief. Nowadays I suppose there would be an army of counsellors to attack them. I don鈥檛 think any help was given to the bereaved or that anything was done for the health or welfare of Bletchley Park staff. I never heard of a Bletchley Park doctor or health worker. I don鈥檛 know of any authority we could have appealed to if we were in difficulties or felt that we had been wrongly treated. We just got on with things.

We were sometimes given a pep talk about how the Bletchley Park information was helping the war effort. One talk I remember was entitled 鈥淗ow we won the Battle of Alamein鈥�. I didn鈥檛 know at the time that George (my husband) had been in the first tank regiment to go through the enemy minefield.

Some good concerts by Bletchley Park staff were staged occasionally. The countryside was pleasant and we were never bombed. But it was a long, weary time.

When the war ended our work ended too. Those who wanted were given jobs in the Civil Service. But some of us just wanted to get home.

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