Between 1999 and 2015, the UK Post Office pursued more than 900 subpostmasters after Fujitsu’s Horizon accounting system reported unexplained shortfalls. About 700 prosecutions were brought directly by the Post Office, and 236 people went to prison. Many others were forced to repay fictitious losses, lost their contracts, homes, or businesses, or were driven into bankruptcy; the consequences were linked to at least 13 suicides. Fujitsu was aware of Horizon bugs as early as 1999, while the Post Office continued to insist the system was robust despite repeated complaints from operators.
Computer Weekly exposed the problems in 2009, and former subpostmaster Alan Bates formed the Justice for Subpostmasters Alliance. In 2017, 555 claimants brought a High Court group action; in 2019, Mr Justice Fraser found that Horizon contained “bugs, errors and defects” and that the Post Office’s contractual practices were unfair. The case settled for £58 million, leaving claimants £12 million after legal costs. Courts began quashing convictions in December 2020, Parliament overturned convictions in England, Wales and Northern Ireland in May 2024, and a statutory public inquiry concluded in December 2024. Compensation eligibility exceeded 4,000 people, with the final cost expected to surpass £1 billion; police also opened an investigation into Post Office and Fujitsu personnel.