On Tuesday, the inquiry heard Mr Dunks was a member of the Fujitsu post office security team, described as an “analyst”, although he admitted having little technical training or knowledge of the Horizon system. He is still employed by the company.

He left school at 16, studied electronics at college and worked as a builder before joining ICL, which later became Fujitsu.

His initial role on the Horizon team was supervising the machine which produced cryptographic keys to secure Horizon machines.

But his duties soon expanded to providing witness statements in cases accusing sub-postmasters of theft and false accounting. This involved extracting audit record query data – detailing what keys had been pressed within Post Office branches – and records of calls to the Horizon helpdesk.

One of his colleagues, who was more directly involved with the helpdesk queries, was not willing to give evidence as, according to Mr Dunks, she found the process “a bit daunting”.

And in Mr Dunks’ witness statement, he said that after the case of Mr Castleton case in 2006, the manager of the Software Support Centre (SSC) team Mik Peach “did not want any of his team to go to court”.

Mr Peach sent an email after the trial saying “the SSC [Software Support Centre, which operated the helpdesk] is NOT in position to undertake this role”.

But Mr Dunks did provide witness statements, compiling them from pre-drafted paragraphs identified by capital letters, assembled following instructions from the Post Office. He was not able to tell the inquiry who originally drafted them.

These covered the operation of the Horizon IT helpdesk, which he admitted having little knowledge of.

In Mrs Misra’s case and others, he told courts that the numerous calls put in by sub-postmasters were not a sign that the counters were not working properly.

Mrs Misra was eight weeks pregnant with her second child when she was sentenced to 15 months in prison in 2010.

When giving opinions about helpdesk matters, Mr Dunks said he informed himself by conversations with SSC staff, often face-to-face, but that these conversations were not recorded by him.

He was asked by barrister Flora Page if he was covering for the SSC “because they were not prepared to stand up and defend Horizon in court”.

“No, that’s not how it worked,” he replied.