But Mr Yates said he had been promised immunity from prosecution if he handed the machine back.

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By 1957 the machine was being outstripped by faster, smaller computers and it was handed over to the Wolverhampton and Staffordshire Technical College (more recently Wolverhampton University) where it was used to teach programming and began to be called the Witch (Wolverhampton Instrument for Teaching Computation from Harwell).

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With the keyboard dock attached, the machine weighs 3.1 pounds, and it's quite manageable, even for carrying one-handed.

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