The former Post Office boss Paula Vennells gave Fujitsu a bonus contract in 2013 to take over an archive of branch data, despite warnings such a move would destroy evidence that might clear operators, whistleblowers have said.
Transaction information was “replatformed” on cost grounds from a “gold standard” external storage system known as Centera to one owned by the Japanese software company running the Post Office’s Horizon IT network.
It is understood Vennells agreed to “migrate” the archive to the Fujitsu system, known as Eternus, despite warnings from at least two senior executives in the Post Office that this would make it virtually impossible to investigate branch transactions should a forensic audit be needed into Horizon’s records.
Data held on EMC Centera – a system used by HM Revenue and Customs – is immutable, meaning it could be proven that it had not been changed before any retrieval for trial. Fujitsu’s Eternus system did not offer such a level of audit integrity.
When prosecuting post office operators, investigators often relied on “filtered data” to prove their targets’ guilt, then the audit records were found to be incomplete by the time the cases were heard in the appeal courts after 2013.
Also, until 2019 the Post Office and Fujitsu had been able to falsely claim that transaction records could not and had not been changed remotely. It was only during the group litigation brought by Alan Bates and others against the Post Office that the truth emerged via a whistleblower, and the scandal of the wrongful prosecutions unravelled.
The latest development raises questions about whether the move to the in-house Fujitsu storage system was purely a cost-cutting exercise or also an act of sabotage.
Vennells, who was the Post Office’s chief executive between 2012 and 2019, is to give evidence to the public inquiry into the scandal in the spring.
Sonia Campbell, a partner at the legal firm Mishcon de Reya and who is representing Vennells at the inquiry, declined to comment.
More than 900 people were wrongfully convicted between 1999 and 2015 in part as a result of faults with the Horizon system, which was ridden with bugs and defects.
By 2013, it was in operation in 11,500 branches in the UK but the Post Office was already facing mounting questions about the safety of the convictions of branch operators based on shortfalls recorded by the accounting system.
The inquiry into the scandal, which has been running since 2021, has heard damning evidence of attempts to cover up the problems with Horizon.
A Post Office source said there had been a need to increase storage capacity in the archive in 2013 but that the decision to shift to Fujitsu’s in-house system raised serious concerns.
The source said: “Paula was told that if you do this you are going to destroy the audit trail, but Fujitsu were saying they could do the job much cheaper. Their Eternus was a good product if you don’t want any audit.
“In technical terms, Centera retains all the history, full history, for audit purposes of all the data, meta data, full transactional use, all time- and date-stamped, along with any user data, logins etc.
“Eternus just store the raw data, so it could be modified and manipulated as if stored in an open database, therefore the data has no integrity.
“Once Eternus was implemented there would be no way of proving Fujitsu’s historic manipulation of data, and by whom and with any logs associated.”
The source said of the switch to Fujitsu’s system: “It begs the question: why would you do this? Cui bono [for whose benefit] given that this was all occurring at the same time as the Post Office was asked to review 70-plus sub-postmaster cases by various MPs and Fujitsu were worried about losing control of Horizon at the time?”
An independent examination by the forensic accountants Second Sight, which was funded by the Post Office in response to pressure from MPs, reported back in July 2013 with concerns about Horizon, but it was not permitted to look into “audit and investigative processes”.
The unreliability of the Post Office’s audit trail continues to plague the organisation.
A Fujitsu software engineer, Gerald Barnes, who wrote the software to migrate the audit data from Centera to Eternus, admitted to the inquiry last month that the court of appeal examining the conviction of an operator at London’s Apex corner branch was given unreliable data last year, with 13 transactions belatedly found to be missing.
A second source, who had warned of the risks involved in migrating the audit store early in 2013, said: “Moving data to another bit of technology doesn’t sound like a big thing, but the Centera technology stored the metadata that gives the context for transactional data. If you just transfer the data it is, in effect, just a set of numbers in rows and columns.”
A Post Office spokesperson said: “We fully recognise the human impact of the Horizon scandal and reiterate our heartfelt apology for the appalling treatment of postmasters. We fully share the public inquiry’s aims to get to the truth of what happened in the past and accountability. We are confident that the inquiry will subject any material it considers to be relevant to scrutiny when it considers it appropriate to do so.”
A spokesperson for Fujitsu said the company would not respond to specific questions but repeated its previous public apology.
He said: “The UK statutory public inquiry, to which our UK subsidiary is providing full cooperation, is examining complex events that have unfolded over many years, and we remain steadfast in our commitment to this cooperation.”