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Who designed and built the Colossus computer?

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The Colossus computer at Bletchley Park, Buckinghamshire, England, c. 1943. — Colossus Funding for this code-breaking machine came from the Ultra project.

The Colossus computer was invented and designed by Tommy Flowers, an engineer and head of the Switching Group at the Post Office Research Station in Dollis Hill, London.1

Flowers pioneered the application of electronics to telephone transmission systems and utilized this expertise to create an all-electronic machine capable of performing cryptographic calculations at high speeds. Despite initial skepticism from officials at Bletchley Park regarding the reliability of electronic valves, Flowers received the necessary support to proceed from W. Gordon Radley, the director of the Dollis Hill research station.21

The first Colossus machine was built at the Dollis Hill facility and delivered to Bletchley Park in early 1944. Subsequent versions, known as the Mark II Colossi, were manufactured at a Post Office factory in Birmingham.21