The number of postmasters wrongfully convicted of theft could be as high as 1,000, the Post Office has admitted.
The figure emerged as the appalling treatment of a former postmistress who developed depression after being dragged to court came to light.
The Government-owned company said an additional 400 former postmasters may have been wrongfully convicted for theft, fraud and false accounting. This is on top of the 550 convictions which were known about.
The number of postmasters wrongly accused of theft could he as high as 1,000 according to the Post Office
From 2000 onwards, hundreds of former postmasters were prosecuted after unexplained shortfalls were found in their branch accounts.
The ex-workers blamed flaws in the IT system, Horizon, but the Post Office denied there was a problem.
In case after case it bullied postmasters into pleading guilty to crimes they knew they had not committed.
Many others who were not convicted were hounded out of their jobs or forced to pay back thousands of pounds of ‘missing’ money.
The Post Office spent £32million to deny any fault in their IT system, before capitulating.
Over the past 20 years, postmasters have been prosecuted after shortfalls were found in their branch accounts and despite pleas from the workers there were IT problems, they were forced into pleading guilty
The shocking number of new cases emerged after bosses delved through records in an attempt to improve fractured relations with postmasters.
In March, 39 cases were sent to the Court of Appeal to be overturned and a decision will be made on 22 more cases shortly.
A crowdfunding campaign is being launched today in a bid to help more victims overturn their convictions at the Court of Appeal.
Alan Bates, of the Justice for Subpostmasters Alliance, is backing the drive to raise an initial £25,000.
He said the alliance will keep fighting until ‘each and every unsafe conviction’ has been overturned.
In another stark example of the human cost of the scandal, it emerged that a Newcastle postmistress dragged to court by the Post Office not only lost the job she loved but was also left suffering depression.
A harrowing interview, made public this week, shows how Sarah Burgess-Boyde was prosecuted despite her plea for help.
Newcastle postmistress Sarah Burgess-Boyde (pictured) was prosecuted and suspended from her job in 2009 after being accused of theft. She suffered from depression and has not worked again despite protesting her innocence
The 56-year-old was suspended in 2009 after a £40,000 shortfall appeared in her branch account.
In the interview, which will be played for the first time in a Radio 4 documentary series this week, she said: ‘I am really proud to be a subpostmaster. I love my job and I love my customers.
‘I’ve got no reason to do anything. If I lose my office I’ll be heartbroken.’
But Post Office staff refused to believe her story, even though she had made a success of her business, tripling her commission to £60,000 in just a few years.
She was threatened with prison and after a two-year ordeal ended up in court – where she was acquitted after the Post Office failed to offer any evidence.
By then she had lost all her savings and was left needing counselling for depression. She has never worked again.
Similar miscarriages of justice, with the Daily Mail leading the way in exposing the scandal as part of the Save Our Post Offices campaign, led to the Post Office capitulating in December last year and handed 550 postmasters £58million in compensation.
But in the first tranche of payments handed out last month, former staff received as little as £500 for their years of anguish.
The Post Office has hired London law firm Peters & Peters to determine how many of the 900 cases should be overturned. It said it was ‘determined to leave no stone unturned regarding historical convictions’.
A spokesman added: ‘Following searches into the oldest cases … the review has identified around 900 cases prosecuted since the introduction of Horizon which may have relied on Horizon data.
‘The detail of the cases is being examined and the proportion involving Horizon is being determined.’
The Great Post Office Trial can be heard on weekdays at 1.45pm from today on Radio 4 and BBC Sounds.