Sub-postmasters wrongfully prosecuted by the Post Office had their lives “utterly destroyed” by the scandal, lawyers acting for them have said.
Hundreds of people were convicted after faulty Horizon software flagged false discrepancies in accounts.
An ongoing public inquiry has been looking at how the court cases were brought against sub-postmasters.
One lawyer said this phase of the probe had “pulled back the curtain” on the scandal.
The fourth phase of the inquiry into the Horizon scandal drew to a close on Friday, having taken evidence from Post Office and Fujitsu employees over several months.
It looked at how investigations were conducted, and how information that the Post Office had that cast doubt on Horizon was not disclosed during court proceedings.
Summing up, Tim Moloney KC, said 76 sub-postmasters had their convictions quashed “only after having their lives utterly destroyed by the scandal at the heart of this inquiry”.
Speaking on behalf of Hudgell Solicitors, he said the firm represented many of the sub-postmasters whose stories were featured in ITV drama Mr Bates vs the Post Office.
In the series, sub-postmistress Jo Hamilton is portrayed as being “surrounded by paperwork, distraught and seeking assistance from a helpline”.
“The help offered was no help at all, doubling a discrepancy before her eyes,” he said, adding this was “real life for Jo”.
“Our clients’ stories repeatedly echo that awful fear, and the impossible question of themselves and Horizon,” Mr Moloney said.
“Time and again they asked for help,” he said. “For many, because none came, they stopped asking.
“Time and again their lives were ruined” by prosecution, he added, despite their telling the Post Office about the discrepancies and maintaining their innocence.
This phase in the inquiry had been “critically important in getting at the real truth for them, about what they went through”, he said.
The inquiry had shown that the Post Office approach to investigation and the recovery of losses, supported by Fujitsu, was “deeply and fundamentally flawed”.
He said the management and oversight of investigations and prosecutions was “wilfully blind” or “disregarding” of the “proper, lawful administration of justice”.
Mr Moloney added the Post Office and Fujitsu, which supplied the software, were focused on their own commercial interests, including brand reputation, rather than on the interests of sub-postmasters.
He said that evidence given to the inquiry could now lay some of the witnesses open to “rigorous criminal investigation”.
Sam Stein KC, representing the Justice for Sub-postmasters Alliance (JFSA) and 157 individual sub-postmasters, said this phase of the inquiry had “pulled back the curtain on the decades of the great Post Office cook-up and cover-up”.
The process wrecked the “physical, mental and economic health” of sub-postmasters, he said.
He said the inquiry had shown “disdain and dislike of sub-postmasters by the Post Office and their employees”, underlined by a Post Office investigator saying sub-postmasters were “all crooks”.
Mr Stein added that the latest phase of the inquiry had shown an “appalling lack of professionalism of lawyers, combined with bullying investigators”, a refusal to investigate the Horizon system because of what that would reveal, and that Post Office employees felt the firm “must be protected at all costs”.
The Post Office was contacted for comment.