As most stand-out "blobs" have already been listed, here's a couple more I'd like to throw in:
Thomas Flowers
After an apprenticeship in mechanical engineering, he earned a degree in electrical engineering at the University of London. In 1926, he joined the telecommunications branch of the General Post Office (GPO) as an engineer, moving to work at the research station at Dollis Hill on the northwest side of London in 1930. From 1935 onward, he explored the use of electronics for telephone exchanges. By 1939, he was convinced that an all-electronic system was possible. This background in switching electronics would prove crucial for his future computer designs.
In February 1941 Flowers' director, W. Gordon Radley, was asked for help by Alan Turing who was based at the government's codebreaking establishment at Bletchley Park. A new decoder system was required for Turing's Bombe system to break Enigma codes. Flowers was sent to help, and although the project was eventually abandoned, Turing was so impressed with the work Flowers had put in, that he introduced him to a friend named Max Newman. Newman was a mathematician who believed that it was possible to mechanise the decoding process of Lorenz ciphers that William Tutte and his codebreaking team had carried out by hand. He had built a machine in an attempt to do this with some success - nicknamed Heath Robinson - but it kept breaking down. Although he was brought in to fix it, Flowers believed that he was capable of building a different and better machine than Newman’s and he started the task in February 1943, finishing the first machine in December the same year.
Called Colossus, Flowers' machine was the world's first programmable computer. It worked off 1,800 thermion valves, though many believed that this was a weakness as valves were notoriously unreliable and prone to breaking down. Although he was forced by Bletchley Park management to proceed on his own (and fund the project with his own money), from his time as a GPO engineer, Flowers knew that valves mainly broke down when a machine was switched on and off all the time. Colossus was left on permanently in what he described as a ‘stable environment’. It proved to be a powerful machine. Newman’s Heath Robinson could read 1,000 characters a minute when it was working, but with its reliability issues, this figure was frequently a lot less, and the whole process needed speeding up with D-Day fast approaching. Colossus was able to read 5,000 characters a minute with excellent reliability. By the end of World War Two, British intelligence had access to ten Colossus machines, and all but two were dismantled once the war was over: they were used at Government Communications Headquarters (GCHQ) before being dismantled between 1959-60.
Flowers was rewarded with an MBE and a £1,000 grant, which did not even cover what he had invested in Colossus. It is a mark of the man that he divided the £1,000 among the team that had helped him and at the end of it, he gave himself £350. Like all the work undertaken at Bletchley Park, Flowers' role in the war was classified and sworn to secrecy. In 1982, when Flowers was asked to give a lecture in America, he had to consult with the MOD as to what topics he could cover, and more especially what topics were still classified. Despite never been honoured by the government for his his work during the war, a road in the area where the research centre for the GPO had been at Dollis Hill is named Flowers Close. An education centre was named after him in Tower Hamlets, London in 2010, which is now the Tommy Flowers Centre, part of the Tower Hamlets Pupil Referral Unit. In 2013, British Telecom (successor to GPO) unveiled a life-sized bronze bust to honour his legacy near its R&D centre in Ipswich.
He died on October 28th 1998, aged 92.
Alan Turing
His early studies were at King’s College, Cambridge where he was elected a Fellow in 1935. In 1936, Turing published his paper
On Computable Numbers, with an Application to the Entscheidungsproblem, in which he reformulated Kurt Gödel's 1931 results on the limits of proof and computation, replacing Gödel's universal arithmetic-based formal language with the formal and simple hypothetical devices that became known as Turing machines. In June 1938 he obtained his Ph.D at Princeton University, New Jersey. His dissertation,
Systems of Logic Based on Ordinals, introduced the concept of ordinal logic and the notion of relative computing, where Turing machines are augmented with so-called oracles, allowing the study of problems that cannot be solved alone by Turing machines.
From September 1938 Turing worked for the Government Code and Cipher School (GCCS) on the problem of the German Enigma machine; on 4th September 1939, the day after the UK declared war on Germany, Turing reported to Bletchley Park, the wartime station of GCCS. Within weeks of arriving, Turing had specified an electromechanical machine that could help crack the Enigma cipher machine more effectively than the Polish
bomba kryptologiczna, from which its name was derived. The Bombe, with an important refinement suggested by mathematician Gordon Welchman in 1940 in the form of a diagonal board (which worked similarly to the Enigma's plugboard), became one of the primary tools, and the major automated one, used to attack Enigma-enciphered messages. A standard Enigma machine consisted of three rotors which could be set in any of 26 positions, whereas the Bombe contained 36 equivalent rotors, each with three drums wired to produce the same scrambling effect as the Enigma rotors. In 1941, Turing’s codebreaking section, ‘Hut 8’, mastered the German submarine communication system that was vital to the battle of the Atlantic.
In 1945 he joined the National Physical Laboratory at Teddington, where he designed and was instrumental in the development of the Automatic Computing Engine (ACE), regarded as the world’s first universal computing machine. He joined the Manchester Computer Laboratory in 1948 - working under the mathematician Max Newman, whom he had known from Bletchley Park days - and two years later he settled in nearby Wilmslow. Turing’s final years were marked by tragedy: he was prosecuted in 1952 for his relationship with another man. Despite having always been open about his sexuality, Turing came to be regarded by his employers as a security risk and barred from working at GCHQ. The ensuing phase of depression ended with his suicide by cyanide poisoning on June 7th 1954, at the age of 41.
William Tutte
He studied at the Cambridge and County High School, and by 1935 gained a scholarship to Trinity College, Cambridge where he studied Chemistry and Mathematics. On the suggestion of one of his tutors, Tutte Joined Bletchley Park during World War Two, but was rejected for work in a code breaking team after being interviewed by Alan Turing. He believed that Tutte would not fit in with the people working in his Enigma team. This decision would lead to Tutte being chosen to join a team led by Colonel John Tiltman, who had been chosen to work on the Tunny project. Tunny was Bletchley Park’s code name for the Lorenz SZ40.
Hitler had ordered the creation of a more sophisticated encoding system that the most senior Nazi military leaders could use with confidence - one far more complicated than Enigma, which was capable of sending out a code in 15 million million different ways. Lorenz 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 had four internal rotors to construct an encrypted code. Lorenz had twelve. It also only needed one operator to use it, whereas Enigma needed three at the sending end and another three at the receiving end.
In 1941, the codebreaking teams who were listening to the Nazi codes being sent throughout occupied Europe began to notice the normal Enigma signals had changed. At first, it seemed that they would be indecipherable, but on August 30th 1941, that all changed. A German operator had sent a coded 4,000 character message which had later been requested again by its recipient due to its length. Normally the internal rotor positions would have been changed before any message was sent, but this didn't happen. On its own intercepting the same message twice wouldn't have helped those at Bletchley, but the operator had decided to use abbreviations and different punctuation to help speed up the process of sending the message again. As a result, when the messages were eventually given to Colonel Tiltman, he was able to decipher them in next to no time. However, they still didn't shed any light on what exactly made Lorenz tick, therefore he handed the task over to Tutte, who was asked to "see what you can make of these".
Tutte then set to work in examining the broken codes, and by identifying the repetitions through intuition and mathematical formulas, he and his team learnt that Lorenz's first internal rotor repeated a pattern every 41 strokes, thus concluding the first rotor wheel had 41 spokes. After 2 months further study, Tutte and his team had successfully worked out of the complete logical structure of the cipher machine. This reverse engineering breakthrough allowed British intelligence to effectively be a fly-on-the-wall at the most important meetings held by the most senior Nazis, as well as being able to influence the enemy through military deception during missions such as Operation Fortitude.
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 moved to Canada where he worked at the Universities of Toronto and Waterloo. The UK government never decorated Tutte for his work at Bletchley Park, but he was elected to be a Fellow of the Royal Society in 1987. In recognition of his work, the Canadian government made Tutte an Officer of the Order of Canada in 2001, and the country's Communications Security Establishment named an internal organisation aimed at promoting research into cryptology, the Tutte Institute for Mathematics and Computing (TIMC), in his honour in 2011. He died on May 2nd 2002, aged 84,
