Reported Horizon errors should have been ‘show-stopper’, public inquiry told

Problems reported with the Post Office’s Horizon IT system before its roll-out should have been regarded as a “show-stopper”, according to a senior executive involved in the roll-out of the controversial system.

The Post Office should have stopped the roll-out of Horizon until reported problems were fixed, and given subpostmasters having trouble balancing their books “the benefit of the doubt” over unexplained losses, because all complex computer systems experience errors, Anthony Oppenheim, former commercial and finance director at ICL Pathway, told the latest Post Office Horizon scandal public inquiry hearing.

Oppenheim added: “We cautioned the Post Office that [Horizon] would not be foolproof.”

ICL, which was later acquired by Fujitsu, developed the Horizon system that is at the centre of the Post Office scandal.

In 1999, the Horizon system was brought in to replace mainly manual accounting practices in Post Office branches. Oppenheim said that if the accuracy of accounts was in doubt, that would be a “show-stopper”.

But despite claims from subpostmasters that the system was causing unexplained accounting shortfalls almost immediately after the roll-out of Horizon in 1999/2000, the Post Office constantly denied the existence of errors in the system, only admitting them in 2019 when a High Court Judge said this was the case.

During the hearing, Oppenheim was asked about his knowledge of the Post Office’s practice of using evidence from the Horizon system to prosecute subpostmasters who had reported losses.

“I had assumed that before getting to prosecution, the people in [the Post Office] would look into the evidence, the audit trails,” he said. “Start with the support people, and they would look at it and put questions to ICL Pathway and we would look into it.

“It didn’t occur to me that the Post Office would rush to prosecution without checking the facts.”

Oppenheim said there were very detailed provisions about what to do under certain operational error conditions, and that Post Office executives  should have understood that these things would occur and there was a process for dealing with them. “There was a general understanding between all the commercial and technical people that with 10 million transactions a day, there would have been errors,” he added.

The former ICL executive said that because in the early stages, there are always teething problems with any new system, “the word of caution was ‘always be on the look-out for new things we didn’t know about’ – and that is the same with the introduction of any large complex system”.

He said that in the early days, the Post Office should have listened to the feedback to see what was going on and given the subpostmasters the benefit of the doubt. “I am not sure I would say the same after five years when the system is bedded in, but even then there would be an inspection of the audit trails and the facts,” he said.

Many subpostmasters were sacked, made to repay supposed losses and made bankrupt. Hundreds were prosecuted for financial crimes, with many sent to prison and given criminal records. A total of 83 former subpostmasters have now had wrongful criminal convictions overturned.

Oppenheim was asked about the practice of the Post Office charging subpostmasters and their legal representatuves, who were trying to prove their innocence, for data from Horizon. He said this was “contractually and morally wrong”.

Computer Weekly first reported on the problems with the Horizon computer system in 2009, when it made public the stories of a group of subpostmasters whose lives were ruined when they were blamed for accounting shortfalls caused by computer errors (see Timeline below).

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.