An early computer known as Colossus was built by Tommy Flowers, an engineer of the British telephone system. He followed the design suggested by Turing in his 1936 paper "On computable numbers, with an application to the Entscheidungsproblem"
That paper is one of the most important scientific papers ever written.
Turing was on a par with scientific greats like Newton and Einstein.
Colossus was used to break coded messages created by the German code machine called "Tunny" it was a 12 rotor machine loosely based on the German Enigma machine. Like Enigma, it was a one-time-pad automated system that relied on a pseudo-random number generator utilizing the rotor wheels in the machine.
The work at Blechley Park was kept secret for so long that it clouded the true history of computing...some facts are still secret.
Turing was later the key man on a team that created the worlds first programmable electronic computer with stored program... The Manchester Baby. also created in the UK.
Alan Turing
Tommy Flowers
The Manchester Baby
The Tunny machine