Sir Alan Bates has told Sky News that the government's new Capture Redress Scheme is "half-baked".
The Post Office scandal campaigner, who may also be a victim of Capture, accused officials of not learning lessons from previous compensation failures.
Capture was a piece of faulty computer software used in about 2,500 branches between 1992 and 1999 before the infamous Horizon scandal.
Many sub-postmasters made up potentially false accounting shortfalls from their own pocket, with dozens, at least, convicted of stealing.
Sir Alan welcomed the launch of the first ever Capture Redress Scheme last week "in general".
However, he added: "It does seem to have gone off half-baked with almost none of the lessons that should have been learnt from the failures of the other Postmaster Schemes having been applied when compiling it."
Sir Alan Bates, who has settled his redress claim with the government in connection with Horizon, also confirmed he may have been a victim of Capture.
He said: "I have documentation which shows that a PC running Capture was part of the inventory when we purchased our sub-post office and I know it was used until it was replaced by the infamous Horizon system toward the end of 2000."
Despite this, Sir Alan said that - with the information he has about the scheme and making a claim - "it does seem I may not be able submit one".
Under the current rules, it appears claimants must submit a fully itemised claim before the Department for Business and Trade (DBT) will decide if they qualify - a process Sir Alan described as "mad".
"We could spend a year compiling a claim only for the DBT to say we weren't eligible in the first place."
He called for a two-stage process: first to confirm eligibility, then to allow victims to build their case with legal support - a model he says would save time, money and avoid unnecessary legal costs.
The revelation that Sir Alan may have been a Capture victim - and didn't realise until later on - raises fresh concerns about how many others remain unaware.
In a statement to Sky News, a government spokesperson said: "After over two decades of fighting for justice, victims will finally receive redress for being impacted by the Capture software and we pay tribute to all of those who have worked to expose this scandal.
"All eligible applicants will receive an interim payment of £10,000. In exceptional circumstances, the independent panel can award above £300,000, which is not a cap.
"We have been in contact with Sir Alan's legal representative and stand ready to provide further information to help all claimants."
It comes as documents seen by Sky News suggest that the Post Office knew about faults in Capture computer software before it was rolled out in 1992.
Notes from a meeting of "the Capture steering group" held in February - months before the system was introduced to branches - described files as being "corrupted".
It highlighted that: "If the power was switched off when a file was open it would be corrupted. In this situation data should be checked and reinput."
Another fault mentioned in the meeting notes was if "part of the system was closed early, to produce client summaries any additional transactions might not be captured for that day".
"If a high error rate was detected the software would need to be reworked."
A document called "Capture Troubleshooting Guide" from April 1993 - over a year after the steering group noted faults - again described "corrupt data" such as incorrect transaction values.
It concluded that the "cause" of this was "switching off the computer or a power cut (even if only for a few seconds) whilst in the Capture programme".
It also put forward instructions to remedy the fault.
Rupert Lloyd-Thomas, campaigner for Capture victims, said: "The Post Office knew ... in 1992, long before the launch, that Capture could be zapped by a power cut.
"They did nothing about it."
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Steve Marston, who was convicted of stealing from his Post Office branch in 1998 after using Capture, said the information "didn't come as any surprise".
"They've known since the very beginning it should never have been released," he added.
A Post Office spokesperson said: "We have been very concerned about the reported problems relating to the use of the Capture software and are sincerely sorry for past failings that have caused suffering to postmasters.
"In September 2024, Kroll published an independent report which examined the Capture software that was used in some Post Office branches in the 1990s and we fully co-operated with Kroll throughout their investigation.
"We are determined that past wrongs are put right and are continuing to support the government's work in this area.
"Post Office has very limited records relating to this system and we encourage anyone who has Capture related material to share it with Post Office and the Criminal Cases Review Commission."
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