A second Post Office IT system could have caused shortfalls for subpostmasters prior to the Horizon scandal that led to Britain’s most widespread miscarriage of justice, an independent investigation has found.

The Capture software was rolled out across some 13.5% of branches from 1993 onwards.

Several subpostmasters told the investigation by Kroll, a risk advisory firm, that although they reported issues with the system to their managers, these were not followed up by the Post Office or taken into account in audits and probes.

There needs to be fast action on these failings, faster than we have seen before

Some were subsequently prosecuted, although the independent report did not make any conclusions about the safety of criminal convictions.

One subpostmaster who was convicted and has since died reported the shortfalls to the Capture help desk but was reportedly told to wait for the system to be rebalanced, according to interview evidence from a surviving relative.

There was a “high capacity” for errors to go undetected, the report said, because of a burden placed on subpostmasters to implement fixes and a reliance on communications from the Post Office to identify bugs.

“We consider that, based on available evidence, there was a reasonable likelihood that Capture could have created shortfalls for subpostmasters,” the Kroll report concluded.

Lawyer Neil Hudgell, whose firm Hudgell Solicitors has represented former subpostmasters during the public inquiry into the scandal, said the findings were “hugely significant”.

He said victims’ lives had been “ruined” by Capture being used as evidence against them, confirming his firm is advising “more than 70 people who have turned to us for help having experienced unexplained losses in their branch accounts during the 90s” when the system was being used.

He said: “The cost to lives from the cases we have seen mirrors that of the devastation caused by the hundreds of prosecutions linked to Horizon.

“Like Horizon, it was a flawed system which was destroying lives whilst officials repeatedly ignored the evidence playing out in front of their eyes.

“Once again, it has only been as a result of the bravery, determination and resilience of those affected, who came forward to speak about what had happened to them, and ultimately would not let injustice go unchallenged, which led to this independent review being commissioned.”

Mr Hudgell said there needed to be “fast action on these failings, faster than we have seen before”.

“Compensation schemes can be created which allow people, should they choose, to seek speedy settlements, or to further investigate their own individual cases. There needs to be fast action on these failings, faster than we have seen before,” he said.

I was horrified to learn about the issues with the Capture system, which pre-dates Horizon

It comes amid a period of heightened scrutiny of the Post Office over the Horizon IT scandal, which saw more than 700 subpostmasters convicted between 1999 and 2015 as Fujitsu’s faulty software made it appear as though money was missing at their branches.

Compensation has since been announced and under the previous Conservative government a new law was passed in May to clear the names of those wrongfully prosecuted.

Post Office minister Gareth Thomas said: “I was horrified to learn about the issues with the Capture system, which pre-dates Horizon. I would like to thank affected postmasters, individuals that have worked with postmasters and parliamentarians for bringing this to light.

“Today, I met with some of the postmasters who used the Capture system, and I thank them for their honesty and bravery in coming forward to talk about the impact it had on their lives and livelihoods.

“The independent report from Kroll Associates, published today, sheds further light on how the faults with the Capture system may have impacted the operation of post offices who used it.

We remain determined that wrongs must be put right as far as that can be possible

“Once postmasters and others have had time to digest the report, I look forward to hearing their views. In parallel I will work closely with colleagues across government to thoroughly examine Kroll’s report and consider what action should be taken. We will work quickly and plan to set out next steps in December.”

A Post Office spokesperson said: “We have, and will continue to, fully support the independent forensic accountancy investigation established by the Government into the Capture software.

“We have been very concerned from the outset about the reported problems relating to the use of the Capture software in the 1990s and are sincerely sorry for past failings that have caused suffering to postmasters.

“We remain determined that wrongs must be put right as far as that can be possible.”