Back in 2012, when the report was released, the Post Office said it had “actively considered the merits of independent verification.” “This was done solely from the perspective that we believe in Horizon, but the review can help give others the same confidence we have,” the post reads. “Our solution between IT, legal, P&BA, security and press [departments] continues to be that no matter what opinions we get, people will still ask “what if” and the defense will always ask questions that require answers that are outside the scope of the report.”

It adds: “Ernst & Young and Deloitte are aware of this issue from the media and we have discussed the pros and cons of the reports with them. Both will offer substantial clauses and will have restrictions on their ability to appear in court, so we didn’t pursue that further.”

Ismay accepted being “asked to present one side of the coin”, as investigative attorney Jason Beer put it.

There was no terms of reference for the report, but Ismay said, “I think at the time I felt the question was quite clear: ‘Please could you list reasons for confidence?’ Ismay admitted that he was given free rein. wrote what he wanted, and only assured of the reliability of the Horizon.

During a hearing on the state public inquiry into the Horizon Post Office scandal, Ismay said that the Post Office’s stance on unexplained losses was that, unless there was a conspicuous error, it was presumed to have been caused by the sub-postmaster, either intentionally as a result of theft or in the result of their mistake.

He acknowledged that when he was the head of risk and control at the post office, questions were raised about the incident at the post office, but his investigation of alleged computer problems was limited to asking the IT department and the Fujitsu staff who supplied the software, the question of whether there were any grounds for accusations of unreliability.

“I did ask the team the question, ‘Look, if we have this allegation, it’s… you know if there’s a basis for it?'” Ismay said. “And colleagues from the IT team at the time came to me with a very strong opinion that it was – the charge made was without any basis.”

When Ismay compiled his 2010 report, he used information from Fujitsu senior technical director Gareth Jenkins. Beer asked him: “In what sense do you think it was objective to ask the person responsible for the development and maintenance of the system whether the system that he developed and maintained was coherent?

Ismay said: “People separated from Gareth that I asked the question told me it was reliable. So, people from our own IT team. Gareth says the same here. Without auditing, I don’t know what else I could do other than accept these statements from individuals. Now I think that the report should have indicated that these are unverified claims, as well as those unverified by me during the comparison of this report, and my report does not say this.

Ismay said the lack of time and his workload were to blame for this major omission. The chairman of the public inquiry, Vin Williams, intervened. He said, “I don’t want to be rude, but some people call it whitewashing. Do you think you did it?”

Ismay said, “No, I think they – accusations were made, but someone like David Smith who joined the organization didn’t hear – and he found his place in the organization.”

Williams replied, “But just telling him one side of the story doesn’t really teach him anything, does it?” Ismay said, “That’s what [David Smith] asked about.”

The investigation questioned the assertion in the report that it was “drafted as an objective internal review [the Post Office’s] processes around sectoral accounting”. Beer asked Ismay, “Do you understand what ‘objective’ means based on real facts, not dependent on personal beliefs or feelings, or not limited by a predetermined set of criteria?”

Ismay agreed with the understanding of this word. Beer replied, “That report didn’t have any of that, did it?”