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Horizon system EPOSS code writers lacked basic programming skills, public inquiry hears

Horizon system code writers lacked basic programming skills, according to the task force set up to investigate reported problems with the controversial software

A task force set up in 2001 to investigate problems with the Post Office Horizon Systems Electronic Point of Sale Service (EPOSS) found poor coding practices and made a damning conclusion on its code writers.

Documents revealed in the latest Post Office Horizon scandal public inquiry hearing revealed that hundreds of bugs in the Horizon EPOSS software existed in 2001, after the software had been rolled out to thousands of Post Office branches.

The task force was set up by Terence Austin, the former systems programme director at ICL Pathway, who was being questioned in the public inquiry today (27 October).

Commenting one an example of code in the EPOSS software the report produced by the task force concluded: “Whoever wrote this code clearly has no understanding of elementary mathematics or the most basic rules of programming."

It said: “Although parts of the EPOSS code are well written, significant sections are a combination of poor technical design, bad programming and ill thought-out bug fixes,” it said. “The negative impact of these factors will continue and spread as long as the [error] fixing culture continues.”

Austin told the inquiry that the Post Office was informed about the problems.

At this time, subpostmasters were being blamed for unexplained accounting shortfalls. From 2000 to 2015, more than 700 subpostmasters were prosecuted for financial crimes. Many lost livelihoods after being forced to repay losses that didn’t actually exist, and hundreds were sent to prison and received criminal records. A total of 82 former subpostmasters have had wrongful criminal convictions overturned, with many more expected. Those that questioned the Post Office over problems with the Horizon system were continuously told they were the only ones experiencing problems.

Initial statement

In 2009, when Computer Weekly first revealed the stories of subpostmasters alleging problems with the Horizon system, the Post Office said: “Horizon is an extremely robust system which operates over our entire Post Office network and successfully records millions of transactions each day. There is no evidence that points to any fault with the technology. We would always look into and investigate any issues raised by subpostmasters.”

The Post Office continued to deny that the Horizon system had errors, claiming it was robust, right up until a High Court judgement in 2019 proved that it was not robust and contained errors that could cause unexplained shortfalls.

A statutory public inquiry into the Post Office scandal is currently in its second phase, investigating the introduction of the Horizon system to the Post Office branch network.

The inquiry has this week already heard from Anthony Oppenheim, former commercial and finance director at ICL Pathway, who said that if the accuracy of accounts was in doubt, that would be a “show-stopper”.

“We cautioned the Post Office that [Horizon] would not be foolproof,” he said.

Oppenheim added that the Post Office should have stopped the roll-out of Horizon until reported problems were fixed, and because all complex computer systems experience errors, subpostmasters having trouble balancing their books should have been given “the benefit of the doubt” over unexplained losses.

Computer Weekly first reported on the problems with the Horizon computer system in 2009.

Read all Computer Weekly’s articles about the scandal since 2009

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