The machine Flowers and his team built was named COLOSSUS and began doing useful work within hours of its installation at Bletchley Park in November 1943. By March 1944 its track record in helping to break the German codes was impressive. In the amazingly short period of 11 months the COLOSSUS had been designed from scratch, constructed and brought into use.

Yet until it had been built, Bletchley Park showed no interest or faith in Flowers and his COLOSSUS design. They wouldn’t even fund the construction, despite Newman having requested it. Indeed, Flowers recalls that it was not until they had been furnished with the first COLOSSUS that they realised what it could do: “They [Bletchley Park] couldn’t believe it!”.

As a result, ten more COLOSSI were commissioned in March 1944. With so much of the code-breaking automated, the whole process became a lot more effective and faster.

The new machines were of considerably enhanced specification, the first of these was built and operational by 8.30am on June 1st, in time to make a significant contribution to the D- Day landings on 6th June 1944.

The COLOSSUS II took in data at the rate of 25,000 bits per second. The reliability of COLOSSUS II was so great that it could typically perform a hundred thousand million bit comparisons between errors. A Pentium PC built around 1999 and programmed to do the same code breaking task would take approximately twice as long as COLOSSUS to achieve the result!

Whilst COLOSSUS was designed for a specific task and did not have stored program capability, it was still able to function beyond its design. For example, it was capable of simple whole number multiplications. It could also be programmed as necessary using its plug boards, though this took a long time.

In all some 10 COLOSSI were built, and used successfully to decipher large numbers of strategically vital messages to and from the German Military High Command.

Indeed, it is now known that their contribution helped significantly to shorten the war.

Tommy Flowers