Ex-staff bringing civil case against the Post Office
Former sub-postmasters who claim they were wrongly accused of false accounting and theft are bringing a civil case against the Post Office.
Noel Thomas, from Gaerwen, on Anglesey, is among those joining forces against their former employer.
Mr Thomas, who was accused of fraud and jailed, claims that a computer glitch added thousands of non-existent pounds to his accounts.
The Post Office has denied the claim.
Mr Thomas, one of Anglesey's county councillors, was jailed for nine months in 2006 after admitting false accounting totalling £48,000.
But he said he experienced problems with the Horizon system, which records all financial transactions in hundreds of Post Offices and sub-Post Offices around the UK.
Tens of other sub-postmasters have also claimed thousands of pounds disappeared from their accounts due to a fault with the software, and said there is no alternative but to begin legal proceedings.
Earlier this year, the BBC's Panorama programme alleged that a document existed which stated that the Post Office did not believe that Mr Thomas was guilty of theft.
Mr Thomas said he hoped that the document would be made public during the civil action.
The Post Office said it is had not heard of any impending court case.
Previously, it said it could not comment on individual cases due to confidentiality, but said a financial loss and false accounting together was often sufficient evidence for a theft charge.