Around 800 Post Office branches have been affected by an unresolved problem with the controversial Horizon accounting and point-of-sale system that is the subject of an ongoing High Court case.

Horizon is currently suffering from a serious operational error affecting customers, subpostmasters and counter staff across the network. The source of the issue appears to be a software patch which was rolled out to the 11,500 branches in June, though the Post Office has not confirmed this.

The problem is causing hundreds of Horizon terminals in Post Office branches across the country to freeze, hang or run very slowly. The problem has not yet been fixed.

Horizon is the subject of a continuing High Court case examining the system’s alleged role in subpostmasters being wrongly prosecuted and fined for accounting shortfalls. The case is part of a multimillion-pound group litigation order brought by 550 subpostmasters, which has already seen two trials, with two more planned over the next year. At the heart of the case is the question of whether Horizon is sufficiently robust (see timeline below for full story).

Last week, the Post Office’s head of retail IT Martin Godbold sent an email to subpostmasters acknowledging that “around 800 branches have reported slow-running over the past few weeks.” He added that “so far we haven’t been able to identify a specific time, a specific counter or a specific transaction that is the cause”.

Computer Weekly spoke to Geoff Crouch, a subpostmaster at Cranbrook Post Office in Kent. He said his Horizon terminal has been running slowly and freezing for “a few weeks now”.

“It’s customer service that’s suffering. When you’re halfway through a transaction, you’re waiting for the screen to catch up with you, and the customer’s looking at you like you’re not very bright. You have to tell them the system’s running slow. It’s embarrassing,” he adds.



Crouch also runs a Co-op franchise: “My Co-op tills are lightning quick compared to the Post Office. Horizon feels like using IT with someone walking in front of you holding a red flag.”

Mark Baker from the Communications Workers Union (CWU), who is a serving subpostmaster himself, said there’s a risk that counter staff could find themselves hitting a screen button multiple times while waiting for the system to respond, which could mean “incorrect figures end up being transmitted, causing a shortage to a postmaster or to a customer.”

Mark Harrison runs two Post Offices – Goole in East Riding and Moorends in South Yorkshire. He describes the current problem as “the worst I can remember” since he became a subpostmaster in 2004.

He told Computer Weekly: “I was on the counter for four hours on Friday morning and I had 20 freezes in that time. It can be any button. We get it on mails, card payments, bill payments. It doesn’t matter what we’re doing. You press an icon [on the screen] and it just sits there for anything up to 25 seconds.”

Harrison said he is losing money because customers are seeing queues in his branches and taking their business elsewhere. On one occasion, he says he lost £117 due to a screen freeze which caused a transaction to disappear on one of his portable Horizon kits.

Harrison said his terminals started running slowly at the end of June. Along with Mark Baker, he believes the problem goes much wider than the 800 branches reported by the Post Office. “When I rang IT support, they admitted it was affecting the whole network,” he said.

The Post Office is aware that the problem is causing consternation. Godbold said in his email to subpostmasters: “Over the past three weeks we have been working with our technology partners to try to identify what may have caused this issue so we can then fix it.

“In practice, this has meant working backwards to see if any of the changes we have rolled out to the network over the past few months have caused the intermittent slow running; and to monitor branches in real-time to see if there are any hardware issues. Rest assured, we take this very seriously and we are working hard to address the issue.”

A Post Office spokesperson added: “We have apologised to our postmasters that some of our branches are experiencing intermittent slow running of the system. We are working hard to find a solution as quickly as possible.”

The Horizon system has a controversial history. After a difficult birth as a government IT project, it was rolled out at the turn of the century to every Post Office branch in the country. Horizon has been operated and maintained by Fujitsu ever since.

In 2009, an investigation by Computer Weekly revealed that the Post Office had prosecuted a number of its subpostmasters for theft and false accounting, but the affected people insisted their problems lay with Horizon, a system they had no control over. More than 30 historic Post Office prosecutions are now being considered by the Criminal Cases Review Commission.

In 2015, the Post Office signed a multimillion-pound Horizon replacement deal with IBM. The deal subsequently collapsed, for reasons which were not been made public, forcing the Post Office to ask Fujitsu to continue maintaining Horizon indefinitely.

In the aftermath of the IBM fiasco, Horizon was migrated away from Windows NT onto Windows 8, and latterly Windows 10. Atos was contracted to run the Horizon IT helpline and a third-party contractor was given the task of replacing the Horizon hardware.

A 2017 Post Office document described Horizon as “clumsy”, “operator unfriendly”, displaying “fragility” and still very much in need of replacement.

Many subpostmasters feel they are getting a poor service. “I’ve never trusted Horizon,” said Crouch. “It’s not proper kit, or proper software. It’s unreliable. This latest episode just underlines it, and I don’t see any mad dash to do anything about it.”

CWU’s Baker added: “When it comes to software updates, no information is supplied to subpostmasters. The software engineers don’t seem to have full knowledge of the impact their fixes will have. It’s as if we postmasters are just beta testers. There needs to be more testing of updates, patches and fixes before they are let loose on the users.”

In July, the Post Office fixed a problem identified by a subpostmaster where cash being accepted by the branch from the Post Office cash centre was not properly recorded in the Horizon system.