The former CEO of the Post Office should be stripped of her CBE over the Horizon scandal, a trade union said, after dozens of subpostmasters had their convictions overturned at the Court of Appeal.

Paula Vennells who became the organisation’s chief executive in 2012, was awarded a CBE in 2019 for “services to the Post Office and to charity”.

Ms Vennells left the company in 2019, months before a damning High Court judgment in a civil claim brought against the Post Office by hundreds of former subpostmasters.

Speaking in the House of Commons last year, Labour MP Kevan Jones said awarding Ms Vennells a CBE was “rubbing salt in the wounds of these innocent people” and called for her honour to be removed.

On Friday, after 39 former subpostmasters had their names cleared, the Communication Workers Union called for Ms Vennells to be stripped of her CBE for “her part in this scandal”.

Andy Furey, CWU’s national officer for postmasters, said: “Our union is demanding that Paula Vennells, the former CEO, be stripped of her CBE – which was awarded to her for services to the Post Office in 2019 – for her part in this scandal.

“We also demand a criminal investigation against those who put loyal, decent workers in this diabolical situation.

“Many senior figures who are complicit in this scandal will now want to run from this situation, but we must not let that happen.

“Heads must roll for the humiliation and misery inflicted on decent, upstanding people who were simply providing much-needed local services and were pillars of their local communities.

“It will be only when justice is done that the suffering of so many can be mended and these decent, loyal postmasters can get real closure.”

At the appeal hearing last month, Sam Stein QC, representing five of the former subpostmasters, told the Court of Appeal: “The Post Office has turned itself into the nation’s most untrustworthy brand … through its own behaviour and its own fault over many years.”

He said the Post Office’s “appalling and shameful behaviour” in prosecuting subpostmasters was “the longest and most extensive affront to the justice system in living memory”.

Mr Stein added: “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.”

Tim Moloney QC, representing 30 of the appellants, told the court that the Post Office’s failure to investigate issues with the Fujitsu-developed Horizon accounting system was “shameful and culpable”.

He said there was “an institutional imperative” within the Post Office “of acquitting Horizon and convicting subpostmasters … in order to protect Horizon and to protect their own commercial reputation”.

The Court of Appeal also heard the Post Office “shredded” potentially incriminating documents relating to its defective Horizon IT system in a bid to “hide the truth”.

The Post Office was “firmly aware that they were going to be exposed” by 2013, but nonetheless deliberately tried to “keep back material” which undermined Horizon’s credibility, the court was told.

A barrister called Simon Clarke gave legal advice to the Post Office’s criminal law team about the disclosure and retention of material about “all Horizon-related issues” in around 2013.

In the advice, Mr Clarke said that, at one weekly conference call at the Post Office’s head office, he was told that minutes of a previous call “should be, and have been, destroyed”, adding that “the word ‘shredded’ was conveyed to me”.

Mr Stein argued this showed the Post Office may have been involved in the “destruction of documents”, which he said “may well amount to conspiracy to pervert the course of justice”.

He added: “There is evidence that this knowledge and this reason for obscuring the truth and hiding the truth went to the very heart of the Post Office.”

In a statement after the ruling, Post Office chairman Tim Parker said the Post Office “continues to reform its operations and culture to ensure such events can never happen again”.

The Post Office’s current chief executive Nick Read said the Court of Appeal’s ruling was “a vital milestone in fully and properly addressing the past”.