Dozens of former subpostmasters who were convicted of theft, fraud and false accounting because of the Post Office’s defective Horizon accounting system are expected to finally have their names cleared.

Subpostmasters’ lives were “irreparably ruined”, as they lost their jobs, homes and marriages after they were prosecuted by the Post Office – which knew the Fujitsu-developed IT system had “faults and bugs from the earliest days of its operation”, the Court of Appeal heard last month.

Lawyers representing 42 former subpostmasters said evidence of serious defects in the Horizon system was “concealed from the courts, prosecutors and defence”, in order to protect the Post Office “at all costs”.

Some of the subpostmasters have since died, “having gone to their graves” with convictions against their name, while “some took their own lives”, the Court of Appeal was told.

At a hearing at the Royal Courts of Justice in London on Friday, at least 39 of the former subpostmasters are expected to have their convictions overturned.

Post Office court case
Former subpostmasters Janet Skinner (left) and Tracy Felstead (Jonathan Brady/PA)

The Post Office has conceded that 39 of the 42 appellants’ appeals should be allowed, on the basis that “they did not or could not have a fair trial”.

But it has opposed 35 of those 39 cases on a second ground of appeal, which is that the prosecutions were “an affront to justice”.

Four of the 42 appeals are not opposed on either ground, while three are fully opposed by the Post Office, which has previously said it will not seek retrials of any of the appellants if their convictions are overturned.

Lord Justice Holroyde, Mr Justice Picken and Mrs Justice Farbey are expected to give a ruling formally quashing the 39 former subpostmasters’ convictions on the basis that they did not have a fair trial on Friday morning.

The Court of Appeal will also rule on whether 35 of them have won their appeals on the grounds that their prosecutions were an affront to justice, as well as on the three fully-contested appeals.

At the hearing in March, Sam Stein QC – representing five of the former subpostmasters – said the Post Office’s failure to investigate and disclose serious problems with Horizon was “the longest and most extensive affront to the justice system in living memory”.

Post Office court case
(left to right) Former subpostmasters Janet Skinner, Seema Misra and Tracy Felstead outside the Royal Courts of Justice in London (Luciana Guerra/PA)

He said the Post Office “has turned itself into the nation’s most untrustworthy brand” by attempting to “protect” Horizon from concerns about its reliability.

He also argued that the Post Office’s “lack of disclosure within criminal cases perverted the legal process”, with many defendants pleading guilty “without exculpatory facts being known or explored”.

Mr Stein told the court: “The fall from grace by the Post Office cannot be ignored.

“It has gone from valued friend to devalued villain.

“Those responsible within the Post Office had the duty to maintain not only the high standards of those responsible for any prosecution, but also to maintain the high faith and trust we had for the Post Office.

“Instead, the Post Office failed in its simplest of duties – to act honestly and reliably.”

Post Office court case
Former subpostmaster Jo Hamilton outside the Royal Courts of Justice, London (Luciana Guerra/PA)

Tim Moloney QC, representing the majority of the former subpostmasters, said the Post Office’s failure to investigate the reliability of Horizon was “shameful and culpable”.

He added: “Those failures are rendered all the more egregious … by the inability of the defendants to make their own investigations of the reasons for the apparent discrepancies.”

Mr Moloney told the court there was “an institutional imperative of acquitting Horizon and convicted subpostmasters … in order to protect Horizon and to protect their own commercial reputation”.

The Criminal Cases Review Commission (CCRC) referred the cases of 42 former subpostmasters to the Court of Appeal last year, following a landmark High Court case against the Post Office.

The Post Office ultimately settled the civil claim brought by more than 550 claimants for £57.75 million, without admitting liability, in December 2019.

Mr Justice Fraser found Horizon contained “bugs, errors and defects” and that there was a “material risk” shortfalls in branch accounts were caused by the system.

As a result of the High Court’s findings, the CCRC referred the 42 former subpostmasters’ convictions to the Court of Appeal.

In a statement ahead of Friday’s ruling, a Post Office spokeswoman said: “We sincerely apologise to the postmasters affected by our historical failures.

“Throughout this appeals process we have supported the quashing of the overwhelming majority of these convictions and the judgment tomorrow will be an important milestone in addressing the past.”

The Court of Appeal hearing is due to begin at 10.30am on Friday morning, but it is not yet known when the former subpostmasters’ convictions will be formally quashed.