Let's get this clear before we start - the headline says "the world's oldest working computer," not "the world's first computer." The oldest working computer is The Harwell Dekatron, later called the Wolverhampton Instrument for Teaching Computing from Harwell (WITCH). It was first powered up in 1951. Over the last three years, the WITCH has been restored by The National Museum of Computing at Bletchley Park where it’s now on display . It's been powered up and is working its way through some of its original 1950s programs.