Tommy Flowers was born in London's West End as the son of a bricklayer. At the age of 16 he took an apprenticeship in mechanical engineering at the Royal Arsenal (Woolwich, UK). At the same time he took evening classes at the University of London in order to obtain a degree in electrical engineering [1].



In 1926, only 20 years old, he took a job at the telecommunications branch of the General Post Office (GPO, now: British Telecom, BT). Four years later, in 1930, he was posted at the GPO research station at Dollis Hill (north-west London), where he explored the use of valve-based electronics for telephone exchanges [2].



Until that time, telephone exhanges were relay-based electro-machanical systems, but Flowers was conviced that an all-electronic exchange with thermionic valves was feasible. This insight would prove crucial for his later war-time work.



In February 1941, he was asked by his director W Gordon Radley to assist BP codebreaker Alan Turing with the design of an electronic decoder for his Bombe machine at Bletchley Park.