Post Office IT boss failed to raise concern over false Horizon statements


A former Post Office IT boss had the opportunity to stop it misleading the public over software errors but went along with false public statements that were in conflict with her professional opinion.

During the latest Post Office Horizon scandal public inquiry hearing, former Post Office chief information officer (CIO) Lesley Sewell revealed she also felt like she was pushed to the outside by management from late 2014, before leaving in 2015 after a five-year stint.

Although the Post Office had knowledge of software bugs from 2006, whenever challenged over the reliability of the Horizon system, it repeated a public statement that Horizon had no errors.

The statement said: “Horizon is an extremely robust system which operates over our entire Post Office network and successfully records millions of transactions each day. There is no evidence that points to any fault with the technology. We would always look into and investigate any issues raised by subpostmasters.”

This was the organisation’s stock response until May 2013, in the run-up to the publication of an independent report by forensic accountants Second Sight, which was to reveal bugs in the Horizon software.

Sewell, who joined the Post Office in 2010 and was CIO from 2012 to 2015, agreed with inquiry barrister Emma Price that people within the organisation knew about bugs as early as 2006, and that she knew of a bug as early as 2011. She was asked by Price: “How can it be, therefore, that the public position of the Post Office up until May 2013 was that there are no bugs in Horizon?”

Sewell answered: “I don’t know the answer to that because from my perspective as an IT professional, I would never say there are no bugs in any system, because you do have faults in computer systems and it’s important how you deal with them.”

Changed public statement

During the inquiry hearing, an email sent by Post Office secretary Alwen Lyons in May 2013, to senior executives including CEO Paula Vennells, general counsel Susan Crichton and communications director Mark Davies, revealed the Post Office had suddenly changed its public statement.

The email described the Post Office’s move away from a statement that said, “there are no bugs in Horizon” to one that said “there are known bugs in every computer system this size and … they are found and put right, and no subpostmaster is disadvantaged by them”.

Sewell said: “When I read this email I couldn’t understand it.”

She said she also disagreed with the Post Office’s strategy to refer to software bugs as “exceptions” or “anomalies” in reports about the Horizon system, but went along with it because it was a direction.

“I just thought it was mad,” said Sewell. “I really didn’t understand the concern of using the word ‘bug’ or ‘fault’ because that’s what they were.”

Minimising seriousness of bugs

She agreed it appears management wanted to minimise the seriousness of bugs through the use of language. “They were faults and I wouldn’t class them as anomalies, but it changed how we had to communicate about bugs,” said Sewell.

During the hearing, it emerged she felt on the outside of the organisation towards the end of her time there, and was tearful when asked about a period she described as “very hard” for her.

Sewell cried on several occasions during the inquiry hearing, and said: “I feel so bad for the subpostmasters.”

In her witness statement to the public inquiry, she wrote that she blocked Vennells after the former CEO contacted her several times in 2021 to request information. “Paula contacted me on four occasions in total,” said Sewell. “I recall blocking her number after the last call as I did not feel comfortable with her contacting me. I had no access to POL papers and was relying on my memory only.”

Sewell joined the Post Office in April 2010 from Northern Rock, where she had been managing director for IT from 2005. On her arrival, she said the Post Office IT team was very small and reliant on Royal Mail Group IT; there was no IT risk register; and there were concerns, in the legal team, over the Horizon contract with Fujitsu, which had not been put out for tender.

The Post Office Horizon scandal was first exposed by Computer Weekly in 2009, revealing the stories of seven subpostmasters and the problems they suffered due to accounting software (see below for timeline of Computer Weekly articles about the scandal, since 2009).


• Also read: What you need to know about the Horizon scandal •

• Also watch: ITV’s documentary – Mr Bates vs The Post Office: The real story


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