Paula Vennells may have known about allegations Horizon could be remotely accessed

In another part of the tapes, Post Office officials relay conversations with Ms Vennells on how the Second Sight probe – commissioned by the Post Office for an independent investigation – could raise the spectre of a “miscarriage of justice”.

Ms Crichton is heard saying: “So Paula agrees that the original scope of the investigation did not go as far as looking at whether it was the miscarriage of justice point, Ron and Ian.

“So that’s, that’s not what she’s looking for. She’s looking for the systematic – or systemic rather, not systematic – systemic weakness in the Horizon systems.

“But not, as I said, it doesn’t go on to that next point around whether or not it’s caused the miscarriage of justice, or suspension of a sub-postmaster.

“Because I think that, once you found it, then it’s up to us to look for and see what impact it might be, if that happens,” Ms Crichton is heard saying.

A statement released on behalf of Ms Vennells by her lawyers said: “I continue to support and focus on co-operating with the inquiry and expect to be giving evidence in the coming months.

“I am truly sorry for the devastation caused to the sub-postmasters and their families, whose lives were torn apart by being wrongly accused and wrongly prosecuted as a result of the Horizon system.

“I now intend to continue to focus on assisting the inquiry and will not make any further public comment until it has concluded.”

Susan Crichton did not respond to Channel 4 News’ requests for comment.

Fujitsu declined to comment.

A Post Office spokesperson said: “We remain fully focused on getting to the truth of what happened and supporting the statutory public inquiry, which is chaired by a judge with the power to question witnesses under oath, and is therefore best placed to help achieve this.”