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On 27 June 2024, former Fujitsu Distinguished Engineer Gareth Jenkins told the Post Office Horizon IT Inquiry that a key phrase in prosecution witness statements—“the computer was operating properly”—referred to the office computer used to prepare the statement, not the Horizon system used in Post Office branches. Inquiry counsel Jason Beer KC challenged that interpretation. The explanation was criticised by independent IT specialists Steven Murdoch and James Christie as extraordinary or implausible, but the hearing was evidence and argument, not a final finding that Jenkins deliberately misled any court.
The wording at the centre of the dispute
The disputed paragraph appeared in material supplied to a court in the 2006 prosecution of subpostmaster Noel Thomas. In substance, it said there was no reason to think the information in the statement was inaccurate because of improper use of “the computer”; that, to the witness’s knowledge and belief, the computer had been operating properly; and that any period of improper operation had not affected the information held on it.
Read in the context of a prosecution based on accounting data, that wording could be understood as an assurance that the computer system generating the evidence was reliable. The ordinary reader would likely connect “the information in this statement” with the facts being presented about a Post Office branch, rather than with the word-processing machine on which a witness typed.
Computer Weekly reported that the language resembled historic computer-evidence wording associated with the Police and Criminal Evidence Act 1984, although the relevant provision had been repealed in 2000. That does not mean Jenkins was making a new certification under a current statutory provision. It illustrates the risk of reusing a legal template without adapting it to the technology, facts and law of the case.
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Who Gareth Jenkins was
Jenkins was a former Distinguished Engineer at Fujitsu Services Ltd. Fujitsu supplied and supported Horizon, the system whose branch accounting data featured in many disputes involving subpostmasters. Jenkins also acted as a technical witness for the Post Office in criminal proceedings.
Those are separate facts from the question of whether he met the standards expected of an expert witness. His employment, his technical relationship with Horizon and his role in giving evidence should not be collapsed into a claim that he was simply “the Post Office’s expert”. The inquiry is examining what he knew, what he said, the limits of his expertise and how his evidence was used.
Jenkins’s explanation to the inquiry
In later witness statements, Jenkins said the paragraph had been misunderstood. He said it was intended to concern the proper operation of the computers used to produce his witness statement, not to certify that Horizon was operating correctly in a branch or across the Post Office estate.
During questioning on 27 June, Beer asked whether “the computer” meant Horizon. Jenkins maintained that he had not been in a position to say that Horizon was operating correctly in the relevant circumstances. The exchange is recorded in the official searchable transcript and on the inquiry’s hearing page.
This was Jenkins’s retrospective account of what the wording was meant to convey. It was not an uncontested description of what the paragraph would have communicated to a court at the time.
Why independent IT specialists found the explanation extraordinary
The ordinary meaning of the words
Steven Murdoch, a UCL professor of security engineering, told Computer Weekly that the wording would ordinarily be read as addressing whether information about events at a Post Office branch was accurate. In that setting, the relevant “computer” naturally appears to be the operational system producing the figures—Horizon—not a desktop used to draft a statement.
The professional-responsibility question
James Christie, an experienced software-development expert, criticised the apparent lack of curiosity about software bugs and the consequences for defendants. His criticism was not a judicial finding of dishonesty. It focused on the gap between a broad assurance about computer-generated evidence and the responsibility of a technical witness to identify defects, uncertainty and the boundaries of what can safely be said.
Both comments were reported by Computer Weekly. They are attributed opinions, not evidence that every technical witness shared the same view.
Why the distinction mattered in Horizon prosecutions
Horizon produced transaction and accounting information used by investigators and prosecutors. When a subpostmaster appeared to have a shortfall, the reliability of that computer-generated information could be central to the case.
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| Proposition | What it concerns | Why it matters |
|---|---|---|
| Horizon was operating reliably | The system generating branch data and alleged shortfalls | Could affect whether figures were treated as dependable evidence |
| The statement writer’s computer was operating properly | The office machine used to type or produce the witness statement | Says little or nothing about whether Horizon’s data was accurate |
The controversy is therefore about a logical and evidential gap: a functioning desktop cannot establish that the remote operational system produced accurate results. The paragraph could be read as assuring the court about the latter even if Jenkins says he intended only the former.
That paragraph alone cannot be said to have caused any particular conviction. Cases also involved Post Office investigations, prosecutors, Fujitsu personnel, disclosure decisions and judicial assessment of the wider evidence. The wording was part of that broader evidential system, not a standalone explanation for the Horizon scandal. A wider overview is available in Computer Weekly’s Horizon explainer.
Boilerplate wording and expert-witness responsibility
Jenkins reportedly described the paragraph as standard Fujitsu wording. Standard language can create a governance problem when it is inserted into evidence without checking that the witness understands exactly what it asserts and that it fits the case.
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There are two distinct possibilities, neither resolved by this hearing alone:
- The wording was intended to address Horizon, in which case the court may have received a broad assurance about system reliability that required careful qualification.
- Jenkins genuinely intended it to address only his desktop computer, in which case the unexplained wording risked misleading readers and should have been clarified before it was relied upon.
An expert can regard a system as generally robust without claiming it is error-free. The expert’s task also includes recognising known defects, relevant uncertainty and the limits of personal knowledge. The precise legal duties depend on the applicable rules and guidance in the individual proceedings.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What the inquiry evidence establishes—and what it does not
Established by the episode
- Jenkins gave oral evidence to the inquiry on 27 June 2024.
- He supplied multiple witness statements, including his first, second, third and fifth statements.
- Beer directly challenged his interpretation of “the computer”.
- Jenkins maintained that the phrase referred to computers used to produce his statement rather than to Horizon’s operation.
Not established by this evidence alone
- That every court interpreted the paragraph in exactly the same way.
- That Jenkins deliberately misled a court.
- That the wording was decisive in any particular conviction.
- That the inquiry had reached a final finding on Jenkins’s conduct.
- That Jenkins knew about every Horizon problem in every case.
The inquiry is an evidential investigation. Its hearing record should not be presented as a criminal verdict or a completed professional-discipline decision.
Read the primary documents
The inquiry’s 27 June 2024 hearing page provides the official materials. Jenkins’s statements are available as his first, second, third and fifth witness statements. The searchable records include the 26 June transcript and the 27 June transcript.
The lasting significance of the exchange is not the functioning of a witness’s desktop. It is whether words presented in criminal proceedings conveyed a reliable assurance about Horizon, whether the witness understood that assurance, and whether the legal process tested its limits.
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