The Harwell computer was still in use
Harwell, Britain's oldest original computer, is being sent to the National Museum of Computing at Bletchley where it’s to be restored to working order. The computer, was designed in 1949, first ran in 1951 to perform mathematical calculations; it lasted until 1973. The system was built and used by staff at the Atomic Energy Research Establishment in Harwell, Oxfordshire. When first built the 2.4m x 5m computer was state-of-the-art, although it was superseded by transistor-based systems. The restoration project is expected to take a year. Speaking to BBC News, Dick Barnes, who helped build the original Harwell computer, said the research was - officially at least - for civilian nuclear power projects. "Officially it was to help with general background atomic theory and to assist in the development of civilian power," he said. "Of course, it [the Atomic Energy Research Establishment] had connections to the nuclear weapons programme," he added.
More info: BBC