The Post Office's Horizon system was robust
| The Post Office's Horizon system was robust | |
|---|---|
| FALSE | |
| "The Post Office's Horizon computer system was robust and reliable, so shortfalls in branch accounts were caused by subpostmasters' theft or errors." | |
| Domain | Technology & Internet |
| Tactic | Fabrication False Context |
| Era | Current |
| First seen | 2000 |
| Origin | Post Office Ltd and Fujitsu statements, prosecutions and court evidence from about 2000 to 2019 |
| Last reviewed | 2026-10-30 |
| Further reading: books on Technology & Internet | |
From 1999, Britain's Post Office used Horizon, an accounting system built by Fujitsu, in its branches. When Horizon showed shortfalls, subpostmasters were required to make up the money. Many were prosecuted for theft, fraud and false accounting.
The Post Office insisted Horizon was robust. Many subpostmasters said they were told they were the only one having problems. Courts later found the system had bugs that could cause the shortfalls.
What the evidence shows
- Prosecutions. Between 1999 and 2015, more than 900 subpostmasters were convicted, most prosecuted by the Post Office itself. Some went to prison, and some took their own lives.
- High Court. In Bates v Post Office, Mr Justice Fraser ruled in December 2019 that Horizon contained "bugs, errors and defects" that could cause apparent shortfalls, and that the Post Office's claims of robustness were not justified.
- Convictions quashed. The Court of Appeal quashed 39 convictions in April 2021. The Post Office (Horizon System) Offences Act 2024 quashed most remaining Horizon-related convictions in England, Wales and Northern Ireland.
- Inquiry. A statutory public inquiry, chaired by Sir Wyn Williams, examined what the Post Office and Fujitsu knew. Evidence showed both were aware of remote access to branch accounts and of known bugs.
Why it matters
Telling individual victims that no one else had problems, while prosecuting hundreds, is one of the clearest institutional examples of gaslighting. It has been called the most widespread miscarriage of justice in British history.
Gaslighting Subpostmasters were told they were the only ones with problems while the Post Office knew of others, a widely cited case of institutional gaslighting. The word comes from Patrick Hamilton's 1938 play Gas Light and the 1944 film Gaslight, in which a husband dims the gas lamps and insists his wife is imagining it. Where the word comes from · More gaslighting cases
Sources
- Bates & Ors v Post Office Ltd (No 6: Horizon Issues) [2019] EWHC 3408 (QB), December 16, 2019.
- Hamilton & Ors v Post Office Ltd [2021] EWCA Crim 577, April 23, 2021.
- Post Office Horizon IT Inquiry, official reports and evidence.