Post Office Horizon scandal: Why hundreds were wrongly prosecuted
PA MediaThe Post Office Horizon scandal has been called the UK's most widespread miscarriage of justice, after hundreds of people were prosecuted on the basis of data from faulty software.
The scandal led to widespread public anger, partly as a result of a hit TV drama, and has been the subject of a lengthy inquiry.
The first part of the report from the official inquiry into what happened is due to be published on Tuesday 8 July.
What happened and how many people were affected?
More than 900 sub-postmasters were prosecuted because of incorrect information from the Horizon computer system.
Many sub-postmasters went to prison for false accounting and theft, and others were financially ruined.
The Post Office itself took many cases to court, prosecuting 700 people between 1999 and 2015. Another 283 cases were brought by other bodies, including the Crown Prosecution Service (CPS).
In 2017, a group of 555 sub-postmasters - led by campaigner Alan Bates, who has since been knighted - took legal action in a landmark court case against the Post Office.
In 2019, the Post Office agreed to pay the group £58m in compensation, but much of the money went on legal fees.
However, the action paved the way for dozens of sub-postmasters to have their convictions quashed in 2021.
The episode came to wider public attention last year after it was depicted in an ITV drama, Mr Bates vs The Post Office.
The outcry triggered by the drama led to legislation being rushed through Parliament to bring in a law quashing convictions from the Horizon scandal.
There are now a number of compensation schemes under way, and as of 2 June 2025, more than £1bn has been awarded to thousands of sub-postmasters across all schemes.
What was the effect on Post Office staff?
Many former sub-postmasters and sub-postmistresses say the scandal ruined their lives.
Some used their own money to cover non-existent shortfalls because their contracts said they were responsible for unexplained losses. Many faced bankruptcy or lost their livelihoods.
Marriages broke down, and some families believe the stress led to serious health conditions, addiction and even premature death.
What compensation schemes are in place?
There isn't a single compensation scheme for sub-postmasters to apply to, and individual eligibility depends on the particular circumstances of each case.
The four main schemes are aimed at groups of victims who had different experiences of the scandal.
As of 2 June 2025, about £1.039bn has been awarded to just over 7,300 sub-postmasters across all four redress schemes. That total breaks down as:
- Horizon Shortfall Scheme - £559m
- Group Litigation Order Scheme - £167m
- Overturned Convictions Scheme - £68m
- Horizon Convictions Redress Scheme - £245m
Prof Chris Hodges, chair of the the independent Horizon Compensation Advisory Board, told the BBC that some individual compensation claims were "well over £1m".
What is Fujitsu's Horizon system?
Horizon was developed by the Japanese company Fujitsu, for tasks such as accounting and stocktaking.
It was introduced by the Post Office in 1999.
Sub-postmasters quickly complained about bugs in the system after it falsely reported shortfalls, often for many thousands of pounds, but their concerns were dismissed.
The Horizon system is still used by the Post Office and maintained by Fujitsu. The Post Office says it has continued to make improvements to the system while it plans "to move to a new system that is being developed".
What is the Post Office Horizon public inquiry?
A public inquiry began in 2022 and heard evidence from Post Office and Fujitsu employees.
Last year, Sir Alan Bates appeared at the inquiry, telling it that the Post Office had spent 23 years trying to "discredit and silence" him.
Paula Vennells, who was Post Office chief executive between 2012 and 2019, gave evidence in May 2024. She was quizzed for three days and at times broke down in tears. She apologised to the sub-postmasters and their families "who have suffered as a result of all that the inquiry has been looking into for so long".
The first part of the inquiry's report is due to be published on Tuesday.
The inquiry became almost box office viewing - racking up more than 20 million views on YouTube.
People with no connection to the Post Office told the BBC how they became engrossed watching.
Who has been criticised for the Horizon scandal?
Ms Vennells resigned from her role at the Post Office in 2019. In January 2024, she said she would hand back her CBE.
In August 2023, the then-Post Office chief executive Nick Read said he would return bonus money awarded for his work on the Horizon inquiry.
Fujitsu Europe director Paul Patterson said the firm had a "moral obligation" to help fund compensation payments.
Lib Dem leader Sir Ed Davey has been criticised for delaying meeting Sir Alan when he was postal affairs minister in 2010. He says he was "deeply misled by Post Office executives".
The BBC discovered that former Prime Minister David Cameron's government knew the Post Office had dropped a secret investigation that might have helped postmasters prove their innocence.