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Tommy Flowers - Technical Innovator

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Tommy Flowers was the creator of the first practical electronic computer. He was the technical innovator behind the design of the Colossus computer used to break the German Lorenz teleprinter codes during the Second World War. It is an achievement that few know thanks to the Official Secrets Act and Tommy Flowers's sense of honour and duty to his country. Colossus was a secret until 1974 and the program's algorithms1 are still secret.

Thomas Harold Flowers was born in London on 22 December, 1905. He seems to have been a practical child, when told of the arrival of a baby sister he declared a preference for a 'Meccano2' set. After school, he embarked on a four-year apprenticeship in Mechanical Engineering at the Woolwich Arsenal and went to night classes to study successfully for a degree in Engineering from London University.

After graduating, he joined the General Post Office (GPO), which was then responsible for all telecommunications within the UK. He worked at Dollis Hill, the GPO's research station, on experimental electronic solutions for long-distance telephone systems. In the 1930s, that meant thermionic valves (US - tubes), which were seen more as analogue amplifiers than electronic switches. These would replace or enhance the electro-mechanical switches then used. These experiments formed the basis for modern direct dialling, but that was some way off. His work also drew the attention of others with quite a different purpose in mind.

Breaking the Codes

Bletchley Park was bought by the Government in 1938 and became the wartime home of Britain's code-breakers. It was known, among other names, as War Station X, Room 47 Foreign Office and - probably the most recognisable - GCHQ. Here were housed the experts with the top secret and vital task of intercepting and translating encoded enemy radio transmissions. They had already broken the U-Boats' Enigma codes, with Polish help, but faced another more challenging task - breaking the German Lorenz teleprinter codes. These codes were used by Hitler to talk to his generals and were known at Bletchley Park as FISH.

The code had already been broken, thanks to a bit of luck and poor transmission discipline, and a machine called TUNNY devised to read the signals. All that remained was to program TUNNY with the code machine settings. It was reckoned that would take weeks, if not months, and by then, the information would be worthless. It was for this task that Tommy Flowers was set to make his mark on the computer world. Even so, the problem of the setting was solved but the machine created, ROBINSON, was giving problems. It was designed on mechanical principles and consisted of two punched tapes being run in synchronisation. It worked, but the synchronisation was difficult to achieve. It was built at Dollis Hill and at some point, Professor Max Newman, the mathematician in charge of the project, was put in touch with Tommy.

Tommy proposed replacing one of the punched tapes with an array of valves and thus did away with the synchronisation problem. The use of valves for digital switching was a groundbreaking step, which offered a huge increase in operating speed over mechanical relays. The experts said it wouldn't work as valves were not known for their reliability. Tommy said that if they weren't switched on and off, they were as reliable as any other piece of electrical gear.

He succeeded in persuading the experts that valves would work, but then ran into another problem. When asked how long it would take to produce his machine, he told them it could be done in a year. This was not acceptable and it was decided that ROBINSON would have to do, despite its drawbacks. Tommy now had the bit in his teeth and was so convinced that his electronic machine would work that he built it anyway. He and his team at Dollis Hill built the first prototype in ten months, using standard telephone exchange components and 1,500 valves, the team working around the clock. It was shown to the experts at Bletchley Park on December 8, 1943. They were astounded. ROBINSON worked at 1,000 characters/second, this machine did it at 5,000!

The machine weighed a ton and took up the best part of a room at Bletchley Park, taking the code name COLOSSUS. It was, in Tommy's words, 'a string-and-sealing-wax affair', but still recognisably an electronic computer. It was operational by June 1944. Tommy did not rest on his laurels. Developing his creation, he had produced another Colossus, the Mark 2, that worked five times as fast as the original, this time using 2,500 valves. By 1945, ten machines were in operation.


The end of the war meant the end of Bletchley Park. During 1946, eight of the Colossus machines were dismantled. Strange to relate, Colossus was made largely out of standard Post Office parts, and when they were stripped down, the parts went back into the spares bin at Dollis Hill. It may be that one of the older exchanges may still be using some of these parts, salvaged from one of the world's first computers. The American Government was given the details of Colossus by the British Government as part-payment for all the food and armaments America had supplied throughout the war.

After the war, Tommy Flowers returned to the Telephone Research Establishment at the GPO. He was awarded £1,000 for his war work, barely sufficient to pay off the debts that he had run up while developing Colossus. He was also honoured with a MBE, thought now by some to be scant reward for war-winning work. Although he proposed making a digital electronic exchange, he was not successful because he couldn't convince the management of their worth nor tell them he had already worked on such systems. He remained there until 1964 then worked for International Telegraph and Telephone until his retirement in 1969. His work was not acknowledged until 1970 as he, and others, were bound by the Official Secrets Act to remain silent. All his family knew was that he was on some 'secret and important' work.

COLOSSUS was initially revealed by the USA's Freedom of Information Bill in 1970 and the release of the information Britain had given the USA. Britain then followed suit. At last, Tommy was finally permitted to discuss his work, 'At the time', he wrote, 'I had no thought or knowledge of computers in the modern sense, and had never heard the term used except to describe somebody who did calculations.' Until then, the world thought the first computer was the American ENIAC, which appeared two years after Tommy's original design. Some say that his work was used in its design, but whatever the truth, Tommy held back and said nothing, supporting his country.

War has a very positive effect on technological development and invention. Unfortunately, the secrecy that surrounds such developments can be stifling, once the danger of discovery is over. For Tommy and Colossus, the work that was done at Bletchley Park was to remain a secret for a very long time. The fact that the Enigma and Lorenz codes were used to predict enemy action and reaction also had to remain secret because, in all probability, the Soviets would have captured the machines and the men that developed them. These would have been used in transmissions that could now be decoded, without the knowledge of the Soviets. It is rumoured that two Colossus machines were still operational at GCHQ at Cheltenham until the 1960s. Why?

Whatever the truth, Tommy Flowers kept his word and remained silent about his contribution to the war effort. No doubt others benefited from his work, but Tommy did not. He never revealed these secrets, only doing so when the restriction was lifted. Even then, much credit for Colossus was given to Alan Turing, who started the idea of a 'computer' in the 1930s and worked on the Enigma project. He died in 1954. Tommy said quite firmly, 'Alan Turing had nothing to do with it!' Alas, Tommy the Technician did not sound as good to some as Alan the Mathematical Alchemist. There is also now a three-hour video interview with Tommy Flowers in the Imperial War Museum in London in which he describes how Colossus was built and exactly how he was treated after the war.

Recognition came after the release of the COLOSSUS information but much too late to give Tommy any real benefit. He received an honorary doctorate from Newcastle University in 1977, and another from De Montfort University in Leicester. More was planned. It became known that he was being considered for a knighthood, possibly in the New Years Honours List. Sadly, Tommy Flowers died from heart failure at home in London on 28 October, 1998. He was 92.

1 An algorithm is a set of steps that define how a task is performed2 Meccano (TM) is a metal 'nuts and bolts' construction system patented by Frank Hornby in 1901. After 78 years, the company ceased trading and MECCANO® is now the registered trademark of Meccano SA, Calais, France.

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