Expert IT witness outsmarted an ‘aggressive’ Post Office to get to truth after inspection ‘madness’

The Post Office’s attempts to protect the Horizon system are well known, in light of the public inquiry and a recent TV drama, but Computer Weekly can reveal how an IT expert was treated during his investigation of Horizon

Karl Flinders,
Chief reporter and senior editor EMEA

Published: 26 Jan 2024 9:58

The Post Office tried to pull the wool over an IT expert’s eyes when it stopped him from properly inspecting its computer system, but the tactic failed and eventually a High Court judge found that the system was error ridden.

The expert was physically prevented from inspecting the controversial Horizon system in the lead up to a multimillion-pound court case, but overcame the Post Office’s aggressive tactic when a retiring subpostmaster gave him access to a system.

Forensic computer expert Jason Coyne was used as an expert witness in the High Court group litigation order where a group of 555 subpostmasters sued the Post Office to prove that the Horizon computer system used in branches contained errors that could cause unexplained accounting shortfalls that they were blamed for.

The trial was arguably the most important event in the unravelling of what is known today as the Post Office Horizon scandal, which saw lives ruined by the Post Office’s insistence that its subpostmasters were to blame for accounting shortfalls and not the computer system they use to manage branch accounts.

In the lead up to the trials, which began in 2018, Judge Peter Fraser, who was managing the legal battle between the Post Office and subpostmasters, ordered that Coyne, representing the latter, could “inspect” the Horizon system, but Post Office legal representatives had a very different interpretation of the meaning of the word than Coyne.

Coyne was invited to Post Office head office at Finsbury Dials, London, to “inspect” the system using a model Post Office branch on site, but was shocked when he was told he could not touch any of the equipment, and would have to instruct a member of Post Office staff to carry out what he wanted to do, which ended up a pointless exercise, he said.

“The Post Office legal representatives, Womble Bond Dickinson, interpreted the judge’s order as being that I was allowed to look at the system, but not touch it. As a result, I was not allowed to put transactions in, physically touch the device, or take the equipment apart, which are the things I would normally do,” said Coyne.

“I kicked off and said, ‘It cannot possibly be the case that this is what Judge Fraser had in mind, because it would be a complete waste of time’.”

Every time Coyne, who has inspected hundreds of pieces of technology over the years, tried to interact with the Horizon terminal, Post Office staff and legal representatives were “physically stopping” him.

Although not easily intimidated, Coyne said it was threatening: “They were standing in front of me and not allowing me to touch the keyboard, printer or screen.”

He said the visit descended into a scene from a comedy film, with him instructing the Post Office trainer what to do, who would then ask for the permission of his superior who would then ask the lawyers for approval before the action was taken.

“Whenever I lifted a hand to point to something, they would jump,” said Coyne. “It was madness and a complete waste of time.” But it did make him suspect that the Post Office was hiding something. “If it was the case that they had confidence in the system, then there would be nothing to hide.”

He said that because Horizon worked when straightforward actions were taken, with errors occurring when things went wrong, he wanted to create what he described as “error conditions”, such as when there is a power outage, but was unable to do so.

A Post Office spokesperson told Computer Weekly: “We apologise if an IT expert was told that they could not touch equipment in our Model Office. That should not have been the case.”

Coyne got around the Post Office’s obstructive behaviour when he was able to find a retiring subpostmaster who agreed to let him visit their office and interact with the Horizon terminal they used. He said the subpostmaster in question had experienced problems with Horizon and suffered unexplained shortfalls. The subpostmaster had retained till rolls, which further assisted Coyne’s investigation.

The shop was shut, but it had not been disconnected from Horizon. Coyne then went about interacting with the system, completing a large number of transactions and introducing error conditions, such as power failures.

What stood out for Coyne is just how it would be “impossible” for a subpostmaster to ever audit their own systems: “The subpostmaster pointed us to a date where they had identified anomalies and we found potential problems just from the till rolls.

“We found things that would need explanation from the Fujitsu side of the system. There were anomalies and concerns that I had – although without seeing the Fujitsu side, I could not confirm errors.”

He could not investigate the hardware because it was locked down and he couldn’t take it to the lab for forensic analysis as the subpostmaster was expecting the equipment to be picked up.

“But we got a good understanding, from a subpostmaster’s perspective, that it would be practically impossible for them to do their own audits because there were questions they could not answer without Fujitsu support,” he said. “We also got to see problems that occurred when there were things like power outages.”

The 555 subpostmasters, represented by Coyne, went on to prove that the system was at fault in the High Court, where Judge Fraser said the Post Office’s claims that the Horizon system was error free and could not cause unexplained errors was “the 21st century equivalent of maintaining that the Earth is flat”.

Coyne’s encounter with the Post Office during his work on the High Court case was not the first time he had come across its reluctance to give investigators access to Horizon. In 2003, Coyne, then of Best Practice Group, was appointed as a joint expert witness for both the Post Office, and for Julie Wolstenholme, who was subpostmaster at the Post Office branch in Cleveleys, Lancashire.

In 2001, the Post Office was suing Wolstenholme for the return of equipment used in the branch after her contract was terminated, but she said her employment was terminated unlawfully in a counterclaim which raised questions about the reliability of the Horizon computer system. The counterclaim, made by the subpostmaster who had suffered major problems with the Horizon system, was for damages related to unfair dismissal.

Coyne was only given access to logs of helpdesk calls made by Wolstenholme to attempt to ascertain if computer errors were causing her problems, because audit data had been destroyed due to the time that had lapsed. But even with limited information, he found that 63 of the calls were “without doubt” related to system failures, either hardware, software or interfaces, and only 13 of the calls he looked at “could or should” have been considered as Wolstenholme requesting help or guidance.

His 2003 report concluded: “I say that the technology installed at Cleveleys was clearly defective in elements of its hardware, software or interfaces, and that the majority of the errors in the fault logs could not be the making of Ms Wolstenholme.”

The Post Office tried to convince Coyne to change his views, which he refused to do.

The Post Office was given legal advice at the time that “in view of the negative expert’s report in this case regarding the computer system in place”, the Post Office’s claim against Wolstenholme would be likely to fail. The Post Office paid Wolstenholne an out of court settlement and, as part of it, forced her to sign a confidentiality agreement to not reveal Horizon issues she was having.

Computer Weekly first exposed the scandal in 2009, revealing the stories of seven subpostmansters and the problems they suffered as a result of the Horizon system (see timeline of all articles below).

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

Watch: ITV’s Post Office scandal documentary, Mr Bates vs The Post Office: The real story.

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