Thousands more subpostmasters could be found to have been victims of the Post Office Horizon scandal after a criminal conviction based on a third faulty Post Office system is sent to the Court of Appeal.
Horizon scandal campaigner Jo Hamilton said she always suspected the third system, known as APS/APT, was causing shortfalls that she was unable to identify due to a lack of paperwork.
Last week, the Criminal Cases Review Commission (CCRC) referred the 2001 conviction of former subpostmaster Gareth Snow to the Court of Appeal. The CCRC said there was evidence that the APS/APT, which Snow used in his branch in Denbighshire, “could cause accounting errors”.
Hundreds of convictions based on evidence from the Horizon system have been overturned. Meanwhile, one conviction based on evidence from a second system known as Capture has been sent to the Court of Appeal, and 30 more are being reviewed.
The first CCRC referral for a subpostmaster conviction based on APS/APT evidence reinforces the view that subpostmasters who experienced problems with any Post Office system are potentially victims of the Post Office scandal.
Thousands more could be affected through APS/APT. In a 1994 news article in the Barry and District News, Richard Dykes, then managing director at Post Office Counters, was quoted as saying the APS/APT system was already installed in 3,000 Post Office branches, with the aim of reaching 6,000 over the following 12 months. It included an electronic terminal connected to telephone lines and was used to carry out transactions such as rent, rates and utility payments.
Not the only one
Rupert Lloyd Thomas, who worked at the Post Office for 30 years from 1974 and has campaigned for users of the Post Office’s faulty Capture system, said: “The APS/APT referral has opened a whole new can of worms. It’s hard to believe that Mr Snow was the only one.”
Campaigning former subpostmaster Jo Hamilton, who had a wrongful conviction based on Horizon evidence overturned in a landmark 2021 case, said she used the APS/APT system in the early 2000s and had suspected it was to blame for shortfalls.
She said the inability to cross-check transactions made her suspect that it was causing unexplained shortfalls. “I always thought something wasn’t right with the system’s transactions. I used to wonder if it was adding stuff in here and there that I didn’t know about, because I didn’t have any slips to check it against.”
Computer Weekly asked the Post Office how many branches used APS/APT, how many users of the system were prosecuted by the Post Office, and whether it would review all cases of subpostmasters’ shortfalls, not just prosecutions, that could be related to APS/APT.
But the Post Office said: “While we cannot comment on individual cases, we have been fully cooperating with the CCRC in this pre-Horizon conviction case by supplying documents and information where this is available.”
It was 2009 when Computer Weekly first told the stories of subpostmasters who had suffered as a result of problems while using the Horizon system, used in all branches since 2000. It took years of campaigning by subpostmasters, a High Court litigation, a public inquiry and a TV drama to get the public’s attention.
Since then, hundreds of wrongful convictions have been overturned, and well over a billion pounds in redress has been paid to victims of the scandal.
It has also emerged that a Post Office system known as Capture, used in a couple of thousand branches before Horizon in the 1990s, was, like Horizon, prone to creating unexplained account shortfalls, for which subpostmasters were blamed and published.
A scheme to compensate affected former subpostmasters has been launched.
Now, the APS/APT referral to the Court of Appeals could widen the scandal further, with thousands more people potentially affected.
There are also questions over a system known as ECCO+, which was used in the Post Office-owned Crown branches in the 1990s. In March 2025, the government minister in charge of the Post Office asked for evidence of problems caused by the software. The National Federation of Subpostmasters, working with law firm Howe & Co, has already received anecdotal evidence about problems experienced by users.
Computer Weekly first exposed the scandal in 2009, revealing the stories of seven subpostmasters and the problems they suffered as a result of the Horizon system (see below a timeline of all articles since 2009).
Also read: What you need to know about the Horizon scandal.