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Post Office Horizon system investigators were blocked and threatened as they witnessed cover-up

Independent investigators who put Post Office and its Horizon system under spotlight faced aggression as they witnessed cover-up

Independent forensic accountants contracted to investigate controversial Post Office Horizon system in 2012 describe Post Office cover-ups, threats, obstruction and the “worst corporate behaviour” seen in their long careers.

During the latest Post Office Horizon scandal public inquiry, investigators Second Sight revealed the lengths the Post Office went to in its efforts to prevent knowledge of flaws in its Horizon computer system and prosecution malpractice being exposed.

Ian Henderson and Ron Warmington of Second Sight were contracted to investigate the Horizon system after MPs forced the Post Office to launch an independent review of the under-fire Horizon system.

In 2009, Computer Weekly revealed the problems being experienced by subpostmasters using the Horizon system. Many were prosecuted when unexplained losses arose and many others were financially ruined. After Computer  Weekly published its investigation and subpostmasters formed a campaign group, pressure was put on the Post Office to investigate allegations about Horizon problems.

Second Sight were appointed by MPs and the Justice for Subpostmasters Alliance (JFSA) campaign group to do an investigation, which was paid for by the Post Office.

However, during the latest public inquiry hearing, it emerged that it wasn’t long before Second Sight began to uncover shocking evidence of Horizon problems and faced Post Office obstructions to their work

‘Clear miscarriages of justice’

Henderson, a forensic accountant who had previously worked for Criminal Cases Review Commission, said that by July 2013, just a year after Second Sight began investigating, it became quickly apparent that subpostmasters had been wrongly prosecuted based on evidence from the Horizon system, with resulting miscarriages of justice.

He wrote in his witness statement to the inquiry: “Post Office Horizon was not the robust, error-free system claimed by [Post Office]. I was also concerned about the potential loss of integrity caused by working practices within Fujitsu, such as remote access without the knowledge or consent of individual subpostmasters. I was beginning to form the view that no prosecution relying on Horizon evidence could be safe.”

He told the inquiry that MPs, including leading voice James Arbuthnot, then MP for North East Hampshire, wanted potential miscarriages of justice investigated by Second Sight. But Henderson said: “[Post Office CEO] Paula Vennells was increasingly attempting to steer us away from considering the safety of convictions.”

He also described Post Office’s attempts to cover-up evidence of Horizon errors and prosecution malpractice, as well as its attempts to silence him.

In June 2015, Henderson received a letter from Post Office lawyer Rodric Williams, stating that a report about the investigation into former subpostmaster Jo Hamilton, who had experienced unexplained accounting shortfalls, should be privileged. It contained a paragraph explaining that no evidence of theft had been found.

Henderson told the inquiry: “I found this assertion to be absurd and to be immensely worrying. It was beginning to look more like a cover-up than a genuine concern about legal professional privilege.”

Hamilton was forced to plead guilty to false accounting to avoid a possible jail sentence. Her wrongful conviction was overturned in 2021.

Henderson was even threatened by Post Office executives. He was told by the Post Office’s acting general counsel Chris Aujard to “be careful” about what he said.

“He told me that if I said anything that harmed [Post Office], [it] would not hesitate to take legal action against me under the terms of my non-disclosure agreement and that I would not be able to afford the legal fees. I took this as a thinly veiled threat to bankrupt me if I continued causing trouble,” he added.

‘Worst corporate behaviour’

Henderson’s business partner, Ron Warmington, also appeared before the inquiry. The Second Sight director and 40-year veteran of investigations at major businesses including Citi Bank and General Electric, told the public inquiry he witnessed the “worst corporate behaviour” he has ever come across.

In a 2015 conversation with a subpostmaster, revealed to the inquiry, Warmington said: “I've been an investigator for about 40 years. I’ve done other jobs at some point, but I’ve been global head of fraud investigation for two of the world’s largest companies, and so I’ve investigated frauds in 110 countries around the world, thousands of fraud cases. I have never come across anything as bad as this.”

Asked by inquiry barrister Jason Beer KC if he stood by this comment, Warmington said that is what he believed then and still believes now.

Warmington said the Post Office knew that revealing the existence of Horizon problems would be an existential threat to its business.

He described the investigators’ struggles getting to the truth: “It was awful, just dealing with people who were not just seemingly failing to understand just about everything we said, but were, we now know – we suspected at the time – were in a sort of cabal that was colluding to or conspiring to thwart every move that we made.

“I had never before encountered such ferocious and determined pushback from a business or client. I was very used to dealing with conflict in my profession, but had never encountered such ferocious resistance to almost every sentence used in every report.”

He said the Post Office would attempt to counter every finding Second Sight made: “Every point we raised, that we knew to be true, received monstrous and illogical pushback. Their approach was, in my experience, unprecedented, particularly during the drafting of our final report and many of the [Case Review Reports].”

Second Sight’s contract was cut short in 2015 when they were sacked. They produced a final report that revealed that the Post office had prosecuted subpostmasters who experienced unexplained accounting shortfalls before getting to the bottom of what caused them.

The Post Office scandal was first exposed by Computer Weekly in 2009, revealing the stories of seven subpostmasters and the problems they suffered due to accounting software. It is one of the biggest miscarriages of justice in British history (see below for timeline of Computer Weekly articles about the scandal, since 2009).

Also read: What you need to know about the Horizon scandal.

Also watch: ITV’s documentary – Mr Bates vs The Post Office: The real story.

Timeline: Computer Weekly articles about the scandal since 2009

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