A recently uncovered document has reignited the firestorm surrounding the Post Office Horizon scandal, revealing that the Post Office and Fujitsu struck a confidential deal 19 years ago to address errors in the Horizon IT system—contradicting years of official denials that such bugs even existed. The 26-page agreement, dated 2006, exposes a commercial framework in which Fujitsu, the developer of the Horizon software, was obligated to fix transaction errors or pay the Post Office up to £150 for each unresolved faulty transaction. This new evidence, first reported by BBC and Channel 4 News, shakes the very foundation of the Post Office’s longstanding narrative and has been described by forensic experts as “dynamite.”
For years, the Post Office insisted—both in courtrooms and before Parliament—that the Horizon system was robust and incapable of causing accounting discrepancies. Sub-postmasters, meanwhile, bore the brunt of this unwavering stance. Between 1999 and 2015, over 900 sub-postmasters were wrongfully prosecuted for theft, fraud, or false accounting after Horizon showed unexplained shortfalls in their branch accounts. Many suffered financial ruin, some were imprisoned, and a tragic number took their own lives. The scandal has since been labeled the largest miscarriage of justice in British legal history.
The newly surfaced contract, which was quietly uploaded to the Post Office Inquiry’s website and only recently scrutinized in detail, lays bare the reality that both the Post Office and Fujitsu were well aware of Horizon’s vulnerabilities. According to Channel 4 News, the agreement explicitly states that if the reconciliation service “identifies that any transaction data held on the ‘central database’ located at the data centre is found to be inconsistent when compared to the records of the transaction that was completed at the branch… the reconciliation service shall obtain authorisation from the Post Office prior to amending the centrally held transaction data.”
This clause is particularly damning, as it directly contradicts the Post Office’s repeated assertions—made during criminal prosecutions and in public statements—that it was impossible to remotely alter branch accounts. The deal also stipulated that Fujitsu would be liable for “liquidated damages” of up to £150 per faulty transaction if errors were not corrected, a fact that was never disclosed to sub-postmasters or the courts. As Paul Marshall, a senior barrister representing sub-postmasters, told the BBC, “The Post Office conducted both the criminal trials of postmasters and the group litigation of 2019 on the basis that it knew of no substantial problems with the Horizon system. Yet this shows that in 2006 there was a very big, recognised problem with Horizon maintaining data integrity between Post Office branch offices and Fujitsu.”
The impact of this cover-up has been devastating. Lee Castleton, a former sub-postmaster in East Yorkshire, was one of the first to be targeted under Horizon-related allegations. In 2006, the Post Office pursued him for £25,000 it claimed was missing from his branch. Castleton, representing himself in court, argued that Horizon was to blame. He lost, was saddled with £321,000 in legal costs, and ultimately declared bankruptcy. Now, Castleton is suing both the Post Office and Fujitsu for damages, and he says the emergence of this document has left him “physically sick.” Speaking to Channel 4 News, he said, “Really, you’ve got a group of people in two companies that wrote a contract for something that they’ve said repeatedly was never required. And it’s just sickening for all the distress and victimisation of the group, of all of our group. They’ve had this document in their possession that they’ve never revealed.”
The agreement’s existence also undermines the Post Office’s claim, made to the media and Parliament as recently as 2015, that Fujitsu could not access or alter sub-postmasters’ transactions without their knowledge. According to the BBC, the document implicitly acknowledges that data held on Horizon’s servers at Fujitsu’s headquarters could fail to match the transactions sub-postmasters carried out at their branches—and that Fujitsu could, with Post Office approval, amend the records to reconcile discrepancies. A later version of the contract even softened this requirement, stating corrections would be made “where this is possible.”
Forensic accountant Ron Warmington, who investigated the Horizon scandal, described the implications of the contract as “dynamite.” Stuart Goodwillie, a campaigner who first discovered the document, and whistleblower Richard Roll, a former Fujitsu worker, both corroborated that Fujitsu routinely corrected thousands of transactions per night to avoid paying penalties to the Post Office. Roll told BBC Panorama in 2015 that this practice was widespread and systematic, further highlighting the scale of the deception.
The emergence of this evidence has not gone unnoticed in the halls of power. Paul Patterson, Fujitsu’s European chief executive, and Post Office chair Nigel Railton are scheduled to appear before MPs on the Business and Trade Committee on January 6, 2026, to answer questions about the scandal. The Post Office, for its part, has issued an unequivocal apology. A spokesperson told the BBC, “We apologise unequivocally for the hurt and suffering which Post Office caused to so many people during the Horizon IT Scandal. Today, our organisation is focused on working transparently with the ongoing public inquiry, paying full and fair financial redress to those impacted, and establishing a meaningful restorative justice programme, all of which are important elements of the ongoing transformation of Post Office.”
Fujitsu, meanwhile, has declined to comment, citing the ongoing forensic investigation by the Post Office Horizon IT Inquiry. “These matters are the subject of forensic investigation by the Post Office Horizon IT Inquiry and it’s not appropriate for us to comment while that process is ongoing,” a spokesperson said.
The government, as the owner of the Post Office, now faces mounting pressure to act decisively in the wake of these revelations. Lawmakers and advocacy groups are calling for not only full redress for the victims but also potential criminal charges against those who orchestrated or concealed the cover-up. The ongoing public inquiry, launched in 2021, is expected to scrutinize this new evidence closely, piecing together a definitive timeline of what was known, when, and by whom.
As the inquiry continues and the public waits for answers, one thing is clear: the emergence of this 2006 contract has changed the landscape. The truth, long buried, is finally coming to light—and with it, the hope that justice may at last be served for the hundreds whose lives were shattered by a system that failed them at every turn.
