Disgraced ex-Post Office boss Paula Vennells is set to be questioned under oath on Wednesday about her role in the Horizon scandal which unfolded under her watch.

Ms Vennells, who was chief executive at the company from 2012 to 2019, will give evidence over the course of three days at the Horizon IT inquiry.

The 65-year-old has been accused of a cover-up by subpostmasters, with campaigner and former subpostmistress Jo Hamilton calling on her to tell the truth.

Post Office Horizon IT scandal
Former subpostmistress Jo Hamilton arrives at Aldwych House (Jeff Moore/PA)

More than 700 subpostmasters were prosecuted by the Post Office and handed criminal convictions between 1999 and 2015 as Fujitsu’s faulty Horizon IT system made it appear as though money was missing at their branches.

Prosecutions continued to happen under Ms Vennells’ watch despite retired judge Sir Anthony Hooper, the chairman of the mediation scheme for people who believed they had been wrongly prosecuted by the Post Office, repeatedly telling her they “didn’t make sense”.

The former chief executive has not yet spoken in detail about her role in the scandal, but previously apologised for the “devastation caused to subpostmasters and their families”.

A document submitted by her lawyers ahead of a preliminary hearing in 2021 said she was “deeply disturbed” by the judgments in the cases against lead campaigner Alan Bates and Ms Hamilton in which Horizon was found to be faulty.

She was made a CBE in the 2019 New Years Honours List “for services to the Post Office and to charity”, but voluntarily handed the honour back after a petition attracted more than 1.2 million signatures.

In a short statement previously issued by Ms Vennells, she said she would “continue to support and focus on co-operating with the inquiry”.

The probe heard she was set to disclose 50 additional documents to the inquiry’s counsel on Friday.

Ms Vennells could be quizzed on her knowledge of the ability to remotely access the Horizon system, alleged false evidence given by expert witnesses during Post Office prosecutions, and the behaviour of the company’s investigators.

She may also be questioned on whether she believed there were any miscarriages of justice during her tenure after chief financial officer Alisdair Cameron told the probe she did not and “could not have got there emotionally”.

The Post Office has come under fire following the screening of ITV drama Mr Bates Vs The Post Office, which put the Horizon IT scandal under the spotlight.

Hundreds of subpostmasters are still awaiting full compensation despite the Government announcing those who have had convictions quashed are eligible for £600,000 payouts.