Former postmaster Paula Vennells is accused of overseeing what has been described as the most widespread miscarriage of justice in UK history.
The scandal returned to public consciousness earlier in the year following the four-part ITV drama Mr Bates Vs The Post Office.
Ahead of Ms Vennells’ testimony to the inquiry on Wednesday, the PA news agency looks at what the scandal is about and why the former chief executive’s evidence is so crucial:
– What is Horizon?
The Horizon IT system is accounting software, owned by Japanese company Fujitsu, which saw accounts automated after subpostmasters entered their sales figures via a touch screen.
– What problems was Horizon causing?
Subpostmasters began experiencing unexplained shortfalls in their accounts and were responsible for the losses under their contract with the Post Office.
– What did Correos do when the sub-administrators suffered deficits in their accounts?
The Post Office ordered subpostmasters to return the lost money and told them they could face prosecution if they did not comply.
– What happened to the subpostmasters who experienced deficits but were unable to return the money?
The Post Office prosecuted more than 700 subpostmasters on charges such as theft and false accounting, and many of them were sent to prison or bankrupt.
– When were deficiencies attributed to faulty computer programs and not to subpostmasters?
In December 2019, a High Court judge ruled that Horizon contained a number of “errors, errors and defects” and that there was a “significant risk” that the system would cause shortfalls in Post Office branch accounts.
– Why has the scandal come to light again?
The Post Office Horizon IT scandal has returned to the spotlight following the release of ITV drama Mr Bates Vs The Post Office, starring actor Toby Jones.
–Who is Paula Vennells?
Vennells was chief executive of the Post Office between 2012 and 2019 and has been accused of covering up the scandal by subpostmasters during her time as head of the company.
– What are you likely to be questioned about in the investigation?
Ms Vennells will testify during a phase of the inquiry looking at governance, meaning she will be questioned about decisions she made during her time in leadership roles at the Post Office.
He could be questioned about his knowledge of the ability to remotely access the Horizon system, alleged false evidence given by expert witnesses during the Post Office prosecutions, and the behavior of the company’s investigators and lawyers.
– Why is Mrs Vennells’ evidence so crucial?
Most of the Post Office witnesses at the inquiry have been unable to remember much about their time at the company as the scandal unfolded and deputy postmasters hope Ms Vennells will shed light on what happened under her watch.
The former chief executive could be key to understanding whether any Post Office staff could be criminally responsible for the wrongful prosecutions and convictions of subpostmasters.
– Has anyone been held criminally responsible for a judicial error?
The Metropolitan Police said it is looking at “possible fraud offenses arising from these prosecutions”; for example, “money recovered from sub-administrators as a result of prosecutions or civil actions.”
Two Fujitsu experts, who were witnesses in the trials, are being investigated for perjury and perverting the course of justice, but no one has been arrested since the investigation began in January 2020.
– What is being done to compensate subpostmasters?
The Government announced that those whose convictions have been quashed will be eligible for payments of £600,000.
Hundreds of people are still waiting for full compensation.