At least 70 people within the Post Office and Royal Mail knew of errors with the Horizon IT system, according to its manufacturer.
Hundreds of sub-postmasters were wrongly prosecuted on the basis of accounting errors produced by the Horizon system.
The barrister for Horizon manufacturer Fujitsu told the inquiry into IT and Post Office failures it had identified a list of people who knew of bugs, errors and defects within the computer program.
These individuals were senior in the organisation, including Post Office board members, senior executives, in-house lawyers, and staff in the security and investigations teams, said counsel for Fujitsu Richard Whittam.
The inquiry received “unequivocal evidence” of these individuals’ knowledge of the Horizon flaws, he added.
It was these flaws that generated imagined financial shortfalls in Post Office branches which were used by the organisation to bring private prosecutions against more than 700 people for theft and false accounting between 1999 and 2015.
Others were bankrupted, lost homes, were isolated from and left communities, suffered ill health and relationship breakdown, and some died by suicide as a result of having to pay back money they never owed.
The scandal has been described as one of the worst miscarriages of justice in recent British legal history.
‘Not the fault of technology’
In concluding Fujitsu’s evidence to the inquiry, Mr Whittam said the Post Office knew of the flaws 25 years ago, and it was not fundamentally the fault of Horizon but of corporate wrongdoing.
“Evidence has demonstrated that these miscarriages of justice were not caused by technological failures exclusively or even primarily but are instead, the product of serious human and organisational failures in conduct, ethics, governance and culture,” he said.
Tuesday is the final day of submissions at the Post Office Horizon IT Inquiry, which has run for two and a half years.
Core participants such as victims, the Post Office, government departments and Fujitsu have been giving their closing submissions.
People distancing for ‘self-preservation’
The legal representative for Paula Vennells who was at the helm of the Post Office during its prosecution of sub-postmasters said she was “entitled to rely” on what she believed was competent legal counsel and IT experts to provide accurate information to her, the board and executive team.
“It is inevitable, having regard to the very human desire for self-preservation, that witnesses will now seek to distance themselves from Ms Vennells,” her barrister said.
In bringing its evidence to a close the Post Office on Tuesday told the inquiry it “must end this closing statement as it began, with an apology”.
It reiterated its “determination to continue with the process of learning the lessons from this inquiry”.
It added: “The Post Office remains firmly committed to ensuring that nothing like this could ever happen again but acknowledges that it will rightly be judged in the months and years to come by what it does, not by what it says it is going to do.”