In the very late 1990s, the British Post Office had a very large computer system called Horizon built for them by Fujitsu. It was the largest non-military computer system in Europe. Over the course of the subsequent years, Horizon proved to be full of both software and hardware issues. The resulting shortfalls of money were blamed on the subpostmasters who had used the system. We will look at the enormous harm that was done to the subpostmasters and try to understand what was wrong with Horizon and what lessons can be learned from what Rishi Sunak, the former Prime Minister of the UK, described as one of the worst injustices in British history.
