Witch computer

This is the Harwell Dekatron Computer, at the National Museum of Computing at Bletchley Park. Known later in its working life as the Witch Computer, it was built in England at the Atomic Energy Research Establishment in the early 1950s "and is one of the first stored-program computers in the world," according to the museum. "It is a general purpose computer capable of many different jobs and its role...was to assist in the design of Britain's first atomic power stations.

"Before this computer was built, all mathematical calculations at the agency were performed by a team of people using mechanical calculators and slide-rules."