Thomas ‘Tommy’ Flowers does not have the same high profile of the likes of World War Two heroes Guy Gibson and Douglas Bader, as examples. However, the part played by Tommy Flowers during his time at Bletchley Park was so important that along with the work of William ‘Bill’ Tutte, historians have argued that their combined work shortened the war by two years, thus saving tens of thousands of lives. An obituary in ‘The Daily Telegraph’ stated: “Tommy Flowers contribution to code breaking in World War Two was immense.” So what was it that this little known person achieved?


Tommy Flowers was born on December 22nd 1905 in Poplar in the East End of London. After school, Flowers worked as an apprentice engineer and in 1926 joined the GPO as an engineer In 1930 Flowers joined and their research centre at Dollis Hill in northwest London. Flowers was particularly interested in electronics and switching electronics.


When World War Two broke out the whole research unit moved to Bletchley Park where it was believed their skills would be useful. Alan Turing asked Flowers for help in building a decoder for the Bombe machine, which was used in the decoding of German messages. The project did not produce a result but Turing was so impressed with the work Flowers put into it that he introduced him to a friend named Max Newman.


Newman was a brilliant mathematician who had closely followed the work of William Tutte on the German Lorenzo SZ40. However, while Tutte’s achievement had been vital, the decoding process around Lorenzo was slow. Newman believed that it was possible to mechanise the process that Tutte and his team had to do by hand. He had a machine that attempted to do this with some success – it was nicknamed ‘Heath Robinson’ – but it kept breaking down.


Flowers was brought in to fix ‘Heath Robinson’. However, he believed that he was capable of building a different and better machine than Newman’s and he started the task in February 1943 and finished the first machine in December 1943.


His end product has been described as one of the greatest inventions of the C20th. His machine was called ‘Colossus’ – the world’s first programmable computer. ‘Colossus’ worked off 1,800 thermion valves and many believed that this was a weakness as valves were notoriously unreliable and prone to breaking down. However, Flowers knew from the work he had done as a GOP engineer, that valves mainly broke down when a machine was switched on and off all the time. ‘Colossus’ was left on permanently in what Flowers described as a ‘stable environment’. Flowers was proved right as ‘Colossus’ proved to be a highly reliable machine. To give some idea of his achievement, the previous largest number of valves used in one single machine was 150. However, such was the scepticism of the managers of Bletchley Park, that they refused to fund the project and while they encouraged Flowers in his work, he had to fund a great deal of the project out of his own money.


‘Colossus’ also proved to be a powerful machine. Newman’s ‘Heath Robinson’ read 1000 characters a minute when it was working. With its reliability issues, this figure was frequently a lot less. The whole process needed speeding up especially as D-Day was approaching and Eisenhower and his team needed as much knowledge as possible about Nazi strengths and weaknesses in northern France.


‘Colossus’ read 5000 characters a minute with excellent reliability.


‘Colossus 1’ and ‘Colossus 2’ (which used 2,400 valves) were ready for D-Day. A great deal of effort meant that both were running by June 1st 1944.


This meant that Allied Supreme Commanders had almost an instant access to information detected over the Lorenzo system – and the Nazis had no idea that this was happening such was their faith in their system. If the Nazis responded to some Allied initiative, the officers in charge of D-Day could adjust their plans accordingly. For example, a speedy decoding of one message just before D-Day on June 5th 1944 continued to show that Hitler was convinced that D-Day would occur in the Pays de Calais and that ‘Operation Fortitude’ had worked. He refused to move more troops to Normandy. No senior Nazi military officer was willing to argue with Hitler regarding this. Therefore, while a massive invasion of Normandy was bound to result in casualties, they were not as bad as might have been expected for such a large-scale invasion. The only sizeable casualties occurred at Omaha Beach – and these had nothing to do with the work done by Flowers.


By the time World War Two ended, British intelligence had access to ten Colossi machines. All but two were dismantled. The remaining two were used at GCHQ and were dismantled between 1959-60.


When World War Two ended Flowers was given a reward of £1000 for his invention – but this sum did not cover the amount of money he had personally invested in the project. This was a considerable sum of money in a country where rationing was still a day-to-day occurrence and where extra money was always a bonus. It is a mark of Tommy Flowers that he divided the £1000 up among the team that had helped him and at the end of it, he gave himself £350 – a good sum of money for 1945 but perhaps not a huge amount for the man credited with inventing the modern computer.


In the post-war paranoia created by the Cold War, Flowers work was highly classified and he remained under the Official Secrets Act. It must have been rather galling for him when in 1948 the Americans announced that they had developed the world’s first computer – something he had done some five years earlier – and he could not say anything about it. It was only in his later years that the truth came out. Even so, in 1982, when Flowers was asked to give a lecture to some students in America, he had to consult with the MOD as to what topics he could cover, and more especially what topics were still classified. Even in 2011, some of the work done by Tommy Flowers remains classified. He had an adult education centre named after him in Tower Hamlets, but it has since shut down. The man who invented the first programmable computer does have a road named after him in the area (Flowers Close) where the old research centre for the GPO had been at Dollis Hill, which is now a housing estate. But few are probably aware as to why the road has that name.


Tommy Flowers died on October 28th 1998 aged 92.


December 2011