Criminal Courts Review Commission set to review subpostmasters' claims of wrongful prosecution

Post Office quick to legal action, says report

The Post Office has been forced on the defensive following recent media reports critical of the way it handled subpostmasters' claims.

These followed a report published last week, carried out by forensic accountants Second Sight on Post Office’s behest, which criticised the way the Post Office handled claims from subpostmasters. Computer Weekly has been following the story since 2009, initially revealing the claims of seven subpostmasters (see Computer Weekly timeline of articles, below).

Since last week’s independent report – which included such criticisms as the Post Office being too quick to take legal action, rather than get to the bottom of the causes of unexplained accounting shortfalls – there have been a number of reports in the national press. The Post Office's PR team published a note on the matter to subpostmasters (see panel below for full text).

The Post Office’s head of communications, Mark Davies, wrote in the Post Office Subspaceonline magazine to inform subpostmasters of the organisation’s belief that much of the media reporting of the alleged problems with its Horizon accounting system had been blown up to present an alarming picture that did not reflect reality.

Davies wrote: “Much of the reporting is designed, as reporting often is, to present a picture which appears alarming: it does not however reflect the reality of the situation, which is some way from that you may read about or see on the TV.”

When asked if it thought the media was sensationalising the alleged problems, the Post Office said media outlets were repeating false claims. “Unsubstantiated, misleading and inaccurate statements have, regrettably, continued to be made to the media and in the public domain throughout this process. This is not in the interests of applicants in the scheme nor the communities we serve.”

Davies also said the Second Sight report did not support its claims with facts. “Unfortunately the forensic accountants have also repeated allegations which are not supported by the facts. We cannot of course support their findings on these points - and you would not expect us to do otherwise,” he wrote.

Post Office covering up miscarriages, says MP

But Alan Bates, a member of the Justice for Sub-postmasters Alliance (JFSA) pressure group said the report was full of evidence – but more was contained in individual case reviews, as there was an agreement that no evidence would be published that could reveal the identities of people involved in individual cases. Each of the 150 cases accepted in the mediation scheme were investigated by Second Sight, and each will have its own report with more detailed evidence of the cases.

When Computer Weekly put this to the Post Office, it said: “It was agreed that Second Sight’s work – for both its reports and its case reviews – should be logical and evidence-based. We have made our position clear in our response to the report.”

Former MP James Arbuthnot – the most vocal of a cross-party group of 140 MPs campaigning on behalf of subpostmasters – said the Second Sight report confirmed the Post Office may perpetrated serious miscarriages of justice. “The Post Office is now trying to cover up these miscarriages of justice, by suggesting that the report contains no evidence. It is packed with evidence, despite the shameful determination of the Post Office to refuse to give the independent investigators the documents they needed – and which the Post Office had promised to provide,” Arbuthnot said.

Davies said the Post Office had only taken “complaints from a tiny number of largely ex-postmasters”. The "tiny number" refers to the 150 applications accepted into the Case Review and Mediation Scheme the Post Office set up.

The Post Office said: “The scheme was widely communicated for three months between August and November 2013. We used our internal channels to encourage people to come forward, we issued a press release and there was media coverage about the scheme. Post Office had previously used these channels to encourage postmasters to come forward with complaints during a period agreed with the JFSA and Second Sight between December 2012 and February 2013. Any postmaster who came forward during this earlier period also had the opportunity to apply to the Scheme. The JFSA also communicated the scheme.”

Post Office dropped case over forensic questions

Bates at JFSA said there had been many more cases and a surge of people contacting the organisation since the Second Sight report was published.

But Post Office said: “This assertion has been made many times over the past three years, and led in part to Post Office using its communications channels to encourage postmasters to come forward with complaints during a period agreed with the JFSA and Second Sight between December 2012 and February 2013. Any postmaster who came forward during this earlier period also had the opportunity to apply to the Scheme. Despite the publicity this matter has received, there have been only a handful of cases raised outside the scheme by either former or serving postmasters.”

Since the report came to light in April 2015, experts have contacted Computer Weekly with detailed knowledge of the Horizon system, raising questions over the integrity of the Post Office's IT system.

A digital forensics expert hired by solicitors 10 years ago in relation to one case – in which a Post Office subpostmaster was accused of false accounting – said he was shocked the disputes are still going on.

Andy Clark, visiting professor in information security at Royal Holloway University of London and director at information security and expert witness company Primary Key Associates, was called as a witness for the defence in a case brought by the Post Office against a subpostmaster. After seeing the Post Office Horizon accounting system in action, he said it was quickly apparent there were questions to ask about its integrity. After asking the Post Office these questions, the Post Office dropped the case.

Clark said he was shocked the issue remained unresolved.

It was clear to me that there were a lot of questions that needed to be answered about the integrity of the system 

 Andy Clark 

Timestamps, tampering and malware

“Nearly ten years ago I was retained by a firm of solicitors as an expert [digital forensics] witness in a criminal matter relating to accusations made against a subpostmaster. At the heart of the prosecution case was Post Office’s Horizon accounting system.”

He said he accompanied the instructing solicitor on a visit to see the Horizon system in action at a Post Office Training Centre. “Within a matter of one hour it was clear to me that there were sufficient significant issues with the design and implementation of that system to bring the integrity and quality of digital evidence into question – for example the vulnerability of Horizon to undetected infection by malware.”

Clark said he wanted to establish the quality and evidential weight of the material on which the prosecution would rely. “This is normal practice for digital forensics experts in the field and, to do so, I asked preliminary questions at the initial meeting at which I first saw a demonstration of the system, as it was deployed at the time.

“I was particularly interested in the reliability of entries in any audit trails, such as could timestamps be relied upon and could entries have been changed without detection? I learned that the source of timestamps on the system I saw could not be considered reliable, being based purely on the local machine clock that could be manipulated and was not synchronised with any external trusted time reference. 

"I also understood that the audit trails were not protected against tampering, and that there had been problems reported of virus infection on systems in the field.”  

When the solicitor made the observations known to the prosecution, the Post Office dropped the case. “It was clear to me that there were a lot of questions that needed to be answered about the integrity of the system," said Clark. 

"After asking early questions, they dropped the case.

Post Office's digital evidence in doubt

“I planned to investigate these aspects of the system first in my detailed technical examination of the system - but never got the chance to do so, as the prosecution dropped the case in advance of me having that opportunity.”

He said that, unless subpostmasters had the support of experts like himself, there could have been miscarriages of justice. "In the Horizon cases that followed the one where I was retained, I think it would have been vital that the defendants were able to challenge the reliability of any digital evidence to establish the facts of the case to the right level of proof required by the court. I don't know the detail of any subsequent cases, but I worry that, if the evidence was not tested thoroughly, then this may well have led to a miscarriage of justice.”

Another IT expert with detailed knowledge of Horizon said: “I have been following the developments with the subpostmaster cases and cannot hold my peace any more."

He said that, during the period he worked with Horizon, the way it communicated to the central systems could account for some of the problems. “When I worked with the Horizon system, it used a bespoke asynchronous communication system. That means it does not communicate in real time, but does so using a series of messages that are stored, and forwarded, when the network connection is available. This is useful where the network connection is not guaranteed to work all the time (that is, the dial-up/broadband connections to each post office). 

"However, asynchronous messaging means that messages from and to the centre may trip over each other. It is perfectly possible that, if not treated properly, messages from the centre may overwrite data held locally.”

I identified a number of functional issues that needed to be addressed, only to be told that I was highlighting too many problems and that the budget had been spent and changes could not be made

 Former subpostmaster Michael Rudkin 

Post Office sacked working group member

The Horizon system used a version of software known as Riposte, from software company Escher.

Former subpostmaster Michael Rudkin, who ran post offices in Barnsley and Leicester, said in 2004-05 he was part of a working group to address difficulties subpostmasters were having with Riposte. He told Computer Weekly: “I identified a number of functional issues that needed to be addressed, only to be told that I was highlighting too many problems and that the budget had been spent and changes could not be made.” He said: “At the time, as you would expect, programmers at the system supplier Fujitsu were prepared to make the changes.”

Rudkin later became chairman of the negotiating committee of the National Federation of Subpostmasters (NFSP). In 2008 his Post Office had an unexplained loss of over £40,000, which had to be repaid. He was suspended in 2008, re-instated in November 2008, suspended again in January 2009 and the Post Office terminated his contract in 2010.  He has not been able to find work since.

Rudkin and his wife have been referred to the mediation scheme.

The Post Office recently said: “Over the past three years there have been exhaustive investigations which have not found any evidence of systemic problems with the Horizon system. The mediation scheme was set up to address individual complaints and that is what we have gone to great lengths to do – a number are now resolved. The complaints are considered on their facts and substance.”

Following the completion of its investigations, the Post Office announced in March 2015 that it would put forward all remaining cases to mediation, with the exception of those which have been subject to a previous court ruling. "Those cases will continue to be considered on a case-by-case individual basis,” said the Post Office.

If you have been affected by or have any knowledge of the issues in this article, please contact Computer weekly in confidence on [email protected]

Computer Weekly timeline of events 

• May 2009: Bankruptcy, prosecution and disrupted livelihoods – Postmasters tell their story
• September 2009: Postmasters form action group after accounts shortfall
• November 2009: Post Office theft case deferred over IT questions
• February 2011: Post Office faces legal action over alleged accounting system failures
• October 2011: 85 subpostmasters seek legal support in claims against Post Office computer system
• June 2012: Post Office launches external review of system at centre of legal disputes
• January 2013: Post Office admits that Horizon system needs more investigation
• January 2013: Post Office announces amnesty for Horizon evidence 
• January 2013: Post Office wants to get to bottom of IT system allegations
• June 2013: Investigation into Post Office accounting system to drill down on strongest cases
• July 2013: Post Office Horizon system investigation reveals concerns
• October 2013: End in sight for subpostmaster claims against Post Office's Horizon accounting system
• October 2013: Former Lord Justice of Appeal Hooper joins Post Office Horizon investigation
• November 2013: 150 subpostmasters file claims over 'faulty' Horizon accounting system
• September 2014: Fresh questions raised over Post Office IT system's role in fraud cases
• December 2014: MPs blast Post Office over IT system investigation and remove backing
• December 2014: Why MPs lost faith in the Post Office's IT investigation, but vowed to fight on
• December 2014: MPs to debate subpostmaster IT injustice claims
• December 2014: MP accuses Post Office of acting "duplicitously" in IT investigation
• December 2014: MPs force inquiry into Post Office subpostmaster mediation scheme
• January 2015: Post Office faces grilling by MPs over Horizon accounting system
• February 2015: Post Office CIO would talk to any subpostmaster about IT problems, promises CEO
• March 2015: Post Office ends working group for IT system investigation day before potentially damaging report
• March 2015: MPs seek reassurance over Post Office mediation scheme
• March 2015: Retiring MP aims to uncover truth of alleged Post Office computer system problems
• April 2015 - Post Office failed to investigate account shortfalls before legal action, report claims