Evidence that Post Office knew its software was ‘totally discredited’ emerges after computer expert comes forward following Sky News report
A devastating report that could overturn hundreds of criminal convictions has been discovered gathering dust in a retired computer expert’s garage – nearly 30 years after it warned the Post Office that its accounting software was “an accident waiting to happen.”
The explosive documents, described by lawyers as “hugely significant” and “seismic,” prove the Post Office knew about catastrophic flaws in its Capture software system as early as 1998 – yet continued prosecuting innocent subpostmasters for years afterwards.
The Forgotten Witness
Adrian Montagu, the computer expert who authored the damning report, came forward after watching a Sky News investigation into Patricia Owen, a subpostmistress convicted of stealing £6,000 from her Canterbury branch in 1998.
For decades, Mrs Owen’s family believed their key defence witness had mysteriously failed to appear at her trial. They remembered his computer “just sitting there” in the courtroom at Canterbury Crown Court, abandoned and unused.
But Mr Montagu insists he did attend – and has the contemporaneous notes to prove it.
“I went to the court and I set up a computer with a big old screen,” he recalls. “I remember being there, I remember the judge introducing everybody very properly… but the barrister in question for the defence, he went along and said ‘I am not going to call you’ – with no reason given.”
The jury never saw his demonstration of how Capture could produce accounting errors. They never heard his expert testimony. And they never read his report.
‘Capable of Producing Absurd Gibberish’
The suppressed report, commissioned by Mrs Owen’s defence team, makes for devastating reading:
- Capture was described as “an accident waiting to happen” and “totally discredited”
- The software was “quite capable of producing absurd gibberish”
- It contained “several insidious faults… which would not be necessarily apparent to the user”
- All of these flaws produced “arithmetical or accounting errors”
- The report concluded that “reasonable doubt exists as to whether any criminal offence has taken place
Most damning of all: this report was served on Post Office lawyers in 1998 – who then continued prosecuting subpostmasters for months and years afterwards.
The Human Cost
Patricia Owen died in 2003, her life destroyed by the wrongful conviction. Her family describe how it “wrecked” her, contributing to her ill health. She went from being a formidable woman who loved being a postmistress to “a shadow of herself” who rarely left the house.
Her daughter Juliet’s anguish is palpable: “To know that in the background there was Adrian with this report that would have changed everything, not just for mum but for every Capture victim after that, I think is shocking and really upsetting – really, really upsetting.
Steve Marston, another Capture victim, was convicted of stealing nearly £80,000 just four months after the Post Office received the damning report. Persuaded to plead guilty with the “threat of jail” hanging over him, he received a suspended sentence.
His reaction to the discovery? Pure rage.
“So they knew that the software was faulty?” he says, his blood boiling. “They kept telling us it was safe… They knew the software should never have been used in 1998, didn’t they?”
The knowledge that this report existed could have “changed everything,” he says. “How dare they. And no doubt I certainly wasn’t the last one… And yet they knew they were convicting people with faulty software, faulty computers.”
A Scandal Before the Scandal
The Capture revelations expose a shocking truth: the Post Office IT scandal didn’t begin with Horizon in 1999 – it started years earlier.
Between 1992 and 1999, Capture was used in more than 2,000 Post Office branches across Britain. How many innocent people were prosecuted based on its faulty data remains unknown, lost in the mists of time and destroyed records.
What we do know is that the Post Office was explicitly warned about these problems in 1998 – yet carried on regardless, graduating to the equally flawed Horizon system that would destroy hundreds more lives over the following decades.
The Legal Fightback
The recovered documents are now with the Criminal Cases Review Commission (CCRC), which is investigating 28 Capture cases with a view to referring them to the Court of Appeal.
Neil Hudgell, the lawyer representing more than 100 victims, doesn’t mince his words about the significance of the discovery.
“I’m as confident as I can be that this is a good day for families like Steve Marston and Mrs Owen’s family,” he says. “I think the documents could be very pivotal in delivering the exoneration that they very badly deserve.”
He adds that there’s “absolutely no doubt” that the “entire contents” of the “damning” report “was under the noses of the Post Office at a very early stage.
It was, he says, a “massive missed opportunity” and “early red flag” that the Post Office ignored – before going on to prosecute hundreds more using the Horizon system.
Government Response
In December 2024, the government acknowledged that Capture could have created shortfalls affecting postmasters and commissioned an independent Kroll report into the software.
Business Secretary Jonathan Reynolds has promised to provide redress for postmasters who suffered losses as a result of Capture errors, with a compensation scheme being developed.
But for many victims, financial compensation can never undo the years of shame, bankruptcy, and destroyed reputations.
The Bigger Picture
The discovery of the Montagu report raises profound questions about the Post Office’s conduct over three decades:
- How many innocent people were prosecuted based on Capture’s faulty data?
- Why did the Post Office continue prosecutions after receiving explicit warnings?
- Who made the decision to suppress this evidence?
- Could the entire Horizon scandal have been prevented if this report had been acted upon?
As one legal expert put it: “This isn’t just about Capture or Horizon – it’s about an institution that knew its systems were broken but chose to destroy lives rather than admit its mistakes.”
What Happens Next
The Criminal Cases Review Commission continues its investigation into Capture convictions, with the potential for dozens more cases to be overturned.
For the families of those wrongly convicted, the wait for justice continues. Patricia Owen’s family hope her name will finally be cleared, 27 years after her conviction and 22 years after her death.
As her daughter Deborah says: “My dad is 81 now and all he wants to see is my mother’s name cleared. It can’t be a process that takes years. It’s already been 27 years for our family.
The discovery of these documents in a suburban garage may seem almost farcical – but for the victims of the Post Office’s systematic persecution, it represents something far more profound: proof, at last, that they were telling the truth all along.
The real scandal isn’t just that innocent people were prosecuted. It’s that the Post Office knew they were innocent – and prosecuted them anyway.
Image credit: Rod Allday via Wikimedia Commons — Licensed under CC BY‑SA 2.0
