Thomas Flowers (1905 – 1998)


Tommy Flowers was a British electronics genius whose Colossus computers enabled the Allies in WWII to break the “Lorenz cyphers” and decrypt messages between the German High Command (OKW) and their troops on the ground throughout Europe.

The Lorenz cyphers were much more complex than the Enigma codes. The breaking of which was an effort which the mathematcian Max Newman set out to achieve. Flowers designed Colossus to help breaking the Lorenz code for Newman.

Colossus was so named for its massive size which deployed some 1800 vacuum tubes (later upgraded to 2400 in the Mark II). His design met resistance among other engineers who claimed that it couldn’t be done and Flowers was squandering good equipmenet. Management then encouraged him to proceed on his own with this project. He then provided much of the required funds by himself.

All together 10 colossi were built until 1945 and by the end of the war an 11th was ready for commissioning. After the war all but 2 were dismantled which were transferred from Bletchley Park and remained in operation at GHCQ until 1959 and 1960.

Flowers received a £1,000 award for his war efforts, barely sufficient to pay off the debts that he had run up while developing Colossus. He was also appointed MBE. But his role in the breaking of the codes and the development of the modern computer remained a secret even to his family until 1974. Flowers received an honorary doctorate from Newcastle University in 1977, and another from Dc Montfort University in Leicester.

Fun facts:

  • His Mark II was 5 times faster than the previous system
  • 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.
  • 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.
  • Until 1970 (freedom of information act), the world thought the first computer was the American ENIAC, which appeared two years after Tommy’s original design.
  • 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.
  • In 1948 the Americans announced that they had developed the world’s first computer – something Flowers had done some five years earlier – and he could not say anything about it.
  • Turing is often credited for some of the design but had actually nothing to do with it. Turing the mathematician sounds better than Tommy the technician. Also Colossus was programmable but not Turing-complete (even Turing was also working at Bletchley Park)

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