The Post Office Horizon scandal was the most widespread miscarriage of justice the CCRC had ever seen, and it represented the biggest single series of wrongful convictions in UK legal history.
Horizon
The scandal related to the wrongful prosecution of former sub-postmasters (people who run independent Post Office branches on behalf of Post Office Limited) for theft, fraud and false accounting between 1999 and 2015.
The IT system used in both independent and Crown Post Offices was called Horizon, operated by Fujitsu on behalf of Post Office. Horizon was piloted in some branches from 1996 and was rolled out across the network of branches from 1999.
By recording transactions, Horizon calculated how much cash and stock should be in an individual branch. The sub-postmaster was expected to count the cash held at their branch each day and enter a daily cash declaration onto Horizon.
If at the end of the relevant trading period (approximately each month) there was a discrepancy between the cash on hand and the figures generated by Horizon, the sub-postmaster was required by their contract to make up the difference.
This could be done either by settling in-branch by putting their own money in to balance the accounts or by settling centrally by asking for the money to be deducted from their monthly renumeration.
There was no option on Horizon to dispute the figures so a sub-postmaster was obliged to accept the figure generated by Horizon before rolling over to the next trading period.
Problems with the Software
From an early stage, Horizon appeared to have significant bugs which could cause the system to misreport, sometimes involving substantial sums of money.
Sub-postmasters found this impossible to challenge as they were unable to access information about the software to do so and there was no chain of evidence as there would have been with previous paper-based accounting methods.
The convictions which the CCRC later reviewed typically arose after auditors from the Post Office found that the physical cash and/or stock in a particular branch was less than that declared by the sub-postmaster, leading to their prosecution.
For 15 years, the Post Office used its private investigation and prosecution powers to prosecute more than 700 sub-postmasters. Hundreds received prison sentences, community punishments orders and criminal records. Many were made bankrupt.
Staff in the Post Office’s call centre were instructed to tell sub-postmasters that they were the only ones experiencing problems with the software.
Problems with Horizon were first reported by Computer Weekly magazine in 2009, reflecting claims from seven sub-postmasters that underlying faults in the system were causing it to overstate the amount of cash or stock that should be on the premises of a particular branch.
A few months later, the Justice for Subpostmasters Alliance (JFSA) was formed to campaign on behalf of those affected. In response to Members of Parliament beginning to raise the issue, Post Office Limited launched a review in 2012.
It also appointed a firm of forensic accountants called Second Sight which, despite being denied access to some of the information they sought, concluded that:
Subsequently, 555 sub-postmasters began group litigation. In December 2019, after two trials at the High Court, the Post Office conceded and settled with the sub-postmasters.
In two judgments in March and December 2019, the High Court found in favour of the sub-postmasters on almost all points, and criticised the integrity and robustness of the Horizon system and its operation.
This group action provided sub-postmasters with evidence to challenge their criminal convictions.
The CCRC’s Reviews
The CCRC’s reviews of Post Office cases were large-scale and complex, with investigations across numerous strands of enquiry.
Applicants submitted that there was new evidence concerning failings in the Horizon computer system which was relevant to the safety of their convictions. It was also claimed Fujitsu had undisclosed information about errors in Horizon.
The CCRC obtained and reviewed a huge amount of material from Post Office Limited. It also met with the JFSA, the Director of Second Sight, and BBC journalists involved in the making of a Panorama documentary about the dispute.
Subsequently, the CCRC visited Fujitsu’s offices to discuss their systems and met a former employee who featured as a ‘whistleblower’ on that documentary.
Expert forensic accountants were then instructed to examine Horizon transaction logs and the High Court judgments were analysed in detail to consider their potential relevance to the criminal cases.
Key findings from these CCRC reviews included:
- There were significant problems with the Horizon system and with the accuracy of the branch accounts which it produced.
- There was a material risk that apparent branch shortfalls were caused by bugs, errors and defects in Horizon.
- Post Office Limited failed to disclose the full and accurate position regarding the reliability of Horizon.
- The level of investigation by Post Office Limited into the causes of apparent shortfalls was poor, and sub-postmasters were at a significant disadvantage in seeking to undertake their own enquiries into such shortfalls.
The CCRC referred 34 cases to the Court of Appeal in June 2020. A further seven cases were referred in July.
The CCRC concluded that there was a real possibility the Court of Appeal would find that these prosecutions were an abuse of process.
Hamilton & Others Vs Post Office Ltd
In its judgment in the case of Josephine Hamilton & Others v Post Office Limited in April 2021, the Court of Appeal, accepting the CCRC’s two grounds for making its references, concluded that:
In all cases in which the reliability of Horizon data was central to an appellant’s prosecution, and in which there was no independent evidence of an actual loss, the trial process could not have been fair (ground 1).
In each case where ground 1 was made out, it was an affront to the public conscience for the appellants to face prosecution (ground 2).
The Court stated that it was:
The Court of Appeal in Hamilton dismissed the appeals in three of the cases the CCRC had referred. In these cases the Court concluded that Horizon data had not been essential to the prosecution in any of those three cases.
In those cases where the appellant had pleaded guilty, the Court of Appeal said that there was clear authority that a conviction following a guilty plea may be quashed on grounds of abuse of process where the plea was “founded upon” the irregularity of non-disclosure.
It went on to say that it had no doubt that all the guilty pleas of the successful appellants in the Horizon cases were founded upon Post Office’s failures of investigation and disclosure and that many of the sub-postmasters may have felt they had no real alternative but to plead guilty.
Subsequent Events
The CCRC has referred 77 Post Office convictions to the appeal courts – resulting in 69 convictions being overturned to date.
The UK Government subsequently announced the launch of a judicial inquiry into the scandal, which was upgraded to a statutory inquiry in June 2021.
In January 2024, ITV released a four-part television drama, Mr Bates vs The Post Office which brought the Horizon scandal to public attention.
On 10 January 2024, the Prime Minister announced that the Government would introduce new primary legislation to make sure that those convicted as a result of the Horizon scandal had their convictions quashed and could be compensated.
On 24 May 2024, the legislation contained in the Post Office (Horizon System) Offences Act 2024 came into effect to quash Post Office Convictions.
This removed the need, for most people, to apply to the appeal court or the CCRC to try and overturn their convictions.
You can find more information about the Horizon scandal here.
You can also find a list of all our Post Office referrals in our Case Library.