‘Justice for Sub-postmasters’ was the plea from two forensic accountants who delivered Cardiac Rehab’s Annual Lecture about their investigation into the Post Office Horizon IT scandal.

In an event that raised more than £7,200 for Cardiac Rehab, Herriard accountants Barbara Jeremiah and Kay Linnell told 250 people at the Alton Maltings Centre that they continue to fight for justice for the Justice for Sub-postmasters Alliance..

The pair described how they followed money that vanished from sub-postmasters’ accounts, prompted by the plight of South Warnborough postmistress Jo Hamilton.

Postmasters’ lives, health and livelihoods were wrecked. Many went to prison and lost everything, being forced to pay back money they never took to the Post Office.

Some had died or committed suicide, and many had not received compensation despite their convictions being quashed.

Dr Kay Linnell catalogued accounting problems created by the government-owned Post Office.

There were inadequate contracts for postmasters, rogue keypad errors, and data being sent down a mobile phone line to a head office in Chesterfield, with substantial errors and delays in reconciliation. In 2013 there were inexplicable net credits on the Post Office profit and loss account.

Dr Linnell said, in her view, the Post Office “had doctored” a report by independent investigator Second Sight.

She added: “It was the Post Office policy to destroy documents after six years - they were specifically warned not to do that in 2013, but continued to do so.

“When we finally got the data from the interim mediation scheme, we could see there were missing and duplicated transactions, even on phone cards, postage labels, GIRO payments, at ATMs, and cheques going missing and never being processed in Chesterfield.”

The Post Office was found to have breached its contract with sub-postmasters to whom it owed a duty of care, explained Dr Linnell.

Barbara Jeremiah said: “We have done thousands of hours of unbilled work, all in our spare time. We’ll never give up.”

There was an absence of government interest despite a Panorama programme and two High Court trials when 736 convictions were quashed.

Mrs Jeremiah said: “Where were government? We were both in the High Court, in Rolls’ Building, the day the Fujitsu whistleblower stood up and said that the computer could corrupt things. When he stood up and said that, there was a lengthy gasp because we knew that that was proof.”

The audience heard Fujitsu and the Post Office could log on to the live Horizon system and make entries.

Mrs Jeremiah said: “But the postmaster would never know anything about these corrective entries as only the half of transactions executed in their post offices was visible to the postmaster.”

Dr Linnell explained the police, The Bar Council and the parliamentary ombudsman are expected to prosecute those responsible after the inquiry.

She added: “Every decent citizen should keep pressure on His Majesty’s government to pay redress, by giving back the money wrongly taken from postmasters as quickly as possible, and also repay costs and losses incurred in compensation for postmasters and their families’ suffering.”