William ‘Bill’ Tutte was one of the great-unsung heroes of World War Two. Tutte worked in complete secrecy at Bletchley Park. Even today, some 66 years after the end of World War Two, some of William Tutte’s work remains classified. One of Tutte’s contemporaries at Bletchley Park, Jerry Roberts, said that Tutte was one of “the forgotten heroes” of World War Two.


Tutte was born on May 14th, 1917 in Newmarket, Suffolk. He studied at the Cambridge and County High School and it soon became apparent to his teachers that he had a great academic ability across the range of subjects studied at the school. In 1935, Tutte gained a scholarship to Trinity College, Cambridge where he studied Chemistry and Mathematics.


During World War Two, on the suggestion of his tutor, Tutte joined Bletchley Park. Tutte was rejected for work in a code breaking team after being interviewed by Alan Turing. In what was to become a major stroke of luck, Turing did not feel that Tutte would fit in with the people working on his Enigma team. This left Tutte free to work on another project and he was chosen to join the team led by Colonel John Tiltman who was chosen to work on the Tunny (Lorenzo SZ40) project. Alan Turing served his country in two major ways during World War Two – his work on decoding Enigma was vital to the Allied success in the Battle of the Atlantic. But his rejection of Tutte for his Enigma team was also to have major consequences – not that Turing would have known this!


Tunny was Bletchley Park’s code name for the Lorenzo SZ40. Hitler had ordered a more sophisticated encoding system that the most senior Nazi military leaders could use with confidence – one far more complicated than Enigma. The end result was the Lorenzo SZ40. Hitler nicknamed the new machine “the secrets writer”. He and his generals were so confident that it could not be broken that it was used to pass highly secret messages throughout Nazi-occupied Europe messages. By cracking Tunny, British intelligence, and therefore Allied military leaders knew about Nazi war plans.


Enigma was capable of sending out a code in 15 million million different ways. The Lorenzo SZ40 took encoding to a totally different level. It was capable of sending out a secret message in 1.6 million billion ways (1,600,000,000,000,000). It was programmed to use binary code, unlike Enigma, and encrypted it. The naval variant of Enigma (and the more complicated) had four internal rotors to construct an encrypted code. The Lorenzo SZ40 had twelve. Lorenzo also only needed one operator to use it, whereas Enigma needed three at the sending end and another three at the receiving end.


The Nazis must have been highly confident that Lorenzo could not be broken and were probably right to believe this what with its massive encryption abilities. What they could not plan for was human error.


In 1941, those in Britain who listened to the Nazi codes being sent throughout occupied Europe noticed that the normal signal associated with Enigma had changed. They realised that this “new type of music” had to be a different Nazi system for sending codes – Lorenzo SZ40. Tutte was just 24 years old when he first started on Lorenzo. He faced an almost unfathomable problem. However, he was helped by one of the German operators who worked on it. On August 30th 1941 a German operator sent a 4,000 character coded message from Athens to Vienna. The recipient asked for a re-send as the message was so large. The sender should have resent his message using a different wheel setting on Lorenzo but he maintained the same settings. This in itself would not have helped those at Bletchley Park if he had sent an identical coded message as they simply would have received the same baffling message twice over. But on the second message, the sender made slight changes by using abbreviations and different punctuation. The sender abbreviated anything that he could presumably to save time and maybe effort second time round. This was the breakthrough Bletchley Park needed as they could see the differences between the two messages and they could build their code breaking from that. Such small details seemingly of no importance to outsiders were vital to the code breakers at Bletchley Park. While “number” changed to “nr” may have meant nothing to anyone outside of Tiltman’s group, to them it was the most vital of the first stage.


The first man to be given these two messages to work on was Colonel John Tiltman, a highly respected code breaker at Bletchley Park. In a brilliant achievement, it took Tiltman just ten days to break the message sent from Athens to Vienna. But as memorable as this achievement was, it did not tell British Intelligence how Tunny/Lorenzo worked. This task was given to Tutte.


Tutte examined the broken code and found patterns and repetitions in it. Using his own intuition and mathematical formulas, Tutte and his team worked out that the first wheel on Tunny repeated a pattern after 41 strokes/resonance’s. Therefore he concluded that the first wheel on Tunny had 41 spokes. He used the same process to work out how many spokes there were on the other 11 wheels. By doing this, Tutte found out how Tunny actually worked – a feat a recent BBC programme about Tutte called “the greatest intellectual achievement of World War Two.”


Captain Jerry Roberts who worked in the same room as Tutte and was a senior cryptographer at Bletchley Park frequently saw Tutte just looking into the distance. Roberts later said:


“I used to wonder if he was doing anything. My word, he was. (Breaking Tunny) was a most extraordinary achievement.”


It soon became clear just how important Tutte’s breakthrough had been. Bletchley Park decoded messages sent by the most senior of the Wehrmacht’s officers – Keitel – and even messages sent by Hitler himself, such was his faith in his “secrets writer”. The breakthrough allowed British Intelligence to effectively be a fly-on-the-wall at the most important meetings held by the most senior Nazis.


The first use of this knowledge would be seen at the Battle of Kursk. Moscow was informed not only that the Germans planned a massive tank/aerial assault on the Red Army within the Kursk Salient but also provided Moscow with the Germans order of battle and that they planned to attack in a pincer movement in an effort to entrap the Red Army in the salient. With such forewarning the Red Army could plan accordingly. Their victory still had to be achieved on the ground, of course. However, the defeat suffered by the Germans at Kursk was a huge blow to their eastern campaign and a massive boost to morale within the Red Army.


Tutte’s work also had a huge impact on D-Day in June 1944. Allied planners knew the whole German defensive structure along the northern French coast. They knew that Hitler had fallen for ‘Operation Fortitude’ – the operation to fool him into thinking that the Allied invasion would be in the Pays de Calais. They also knew how many tanks and aircraft the Germans had in France and where they were based. The even knew how many aircraft were actually unable to fly because they were being serviced.


Those at Bletchley Park even used Tunny to predict what Hitler would do next. They knew that he was not willing to withdraw German troops from Italy. Therefore the campaign there continued in the full knowledge that Hitler would use resources there defending Italy that were much needed in France after the success of D-Day.


In a huge understatement, Captain Jerry Roberts said that breaking Tunny “was pretty jolly important”.


After the war, Tutte returned to Trinity College to continue his pre-war work. However, he received an invitation to teach in Canada and in 1948 Tutte moved to Canada where he worked at the Universities of Toronto and Waterloo.


The UK government never decorated Tutte for what he did at Bletchley Park but he was elected to be a Fellow of the Royal Society. “Certainly we are talking about a genius.” Professor Bill Cunningham, University of Waterloo, Canada. In recognition of the work he did, the Canadian government made Tutte an Officer of Canada in 2000. He briefly returned to live in Newmarket after his wife died but quickly returned to Canada.


William ‘Bill’ Tutte died on May 2nd 2002 and is buried in Canada.


December 2011.

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