The boss of Fujitsu in Europe has admitted staff knew of bugs, errors and defects (BEDS) in the Horizon IT system as far back as 1999.
Appearing before the inquiry into the Post Office scandal, Paul Patterson said it was “shameful and appalling” that the known glitches were not included in the witness statements used to prosecute hundreds of sub-postmasters over nearly two decades.
He said the “vast majority” of errors had been shared with the Post Office contemporaneously.
“There’s lots of evidence of us informing the Post Office of that data that we’ve just discussed, bugs and errors, and how those bugs and errors did or did not impact the financial position as reported,” he said.
Mr Patterson said he did not know why the details of the BEDS did not find their way into witness statements, and that some references to them were edited out of evidence “by others”.
He said that was “shameful, appalling”.
“My understanding of how our laws work in this country, that all of the evidence should have been put in front of the subpostmaster, that the Post Office was relying on to prosecute them.”
Mr Patterson could not say when Fujitsu became aware the Post Office was prosecuting its staff with faulty evidence.
Asked when they put two and two together, he said: “I do not believe Fujitsu knew at the time, but certainly latterly… the company became more aware that it was being used nearly solely for prosecutions.”
The inquiry, which began in 2021 and is chaired by retired judge Sir Wyn Williams, is looking to establish a clear account of the implementation and failings of the Horizon system.
Discrepancies in the software led to more than 700 branch managers being wrongfully convicted for theft and false accountings between 1999 to 2015, in one of the biggest miscarriages of justice in British legal history.
The Post Office denied the subpostmasters’ reports of faults in the system and pursued them for the shortfalls, resulting in people being sent to jail and financially ruined.
Mr Patterson has been in his current role since 2019 and most of his evidence comes from documents given to him by other colleagues.
His appearance at the inquiry comes after he faced a grilling from MPs earlier this week, in which he acknowledged his company had a “moral obligation” to compensate victims.
Much of the questioning on Friday focused on Fujitsu’s ARQ audit data and the use of it in Post Office prosecutions.
Mr Patterson said the data accessible to subpostmasters during criminal proceedings was not “sufficient to understand whether Horizon was operating correctly at the relevant branch”.
That is despite a Post Office expert describing the data as a “secure gold standard for branch accounts” during High Court proceedings launched by postmasters in 2017.
Mr Patterson went on to elaborate by referring to Lee Castleton’s case, a sub-postmater who was blamed for a £26,000 shortfall which did not exist.
The story was featured in the recent ITV drama Mr Bates Vs The Post Office, which returned the Horizon scandal to the national spotlight.
Mr Patterson said: “I think in Mr Castleton’s case and looking at that spreadsheet and…it’s certainly not a gold or any standard.
“It’s a very simple excel file which tells you not very much at all.”
The Fujitsu boss acknowledged “missed opportunities” in helping the sub-postmasters, as he was shown a document from 2007 referring to the Post Office’s prosecution of Mr Castleton.
The document contained notes from Fujitsu engineer Anne Chambers, who said she was approached to speak to a solicitor about a call she had with Mr Castleton but “repeated assurances that this would all be settled before going to court proved to be unfounded”.
She also expressed concern that there was “no technical review” of the Horizon evidence between the initial call and the case going to court, and she was worried there was something she “might have missed”.
It was put to Mr Patterson that those comments are similar to what he is saying now.
“I would agree that this is a series of missed opportunities”, he said.