On Thursday, the Horizon Inquiry was shown a transcript of a phone call, during which the barrister Mr Clarke discussed what Gareth Jenkins knew about the software bugs.
The transcript confirmed that Mr Jenkins knew of two bugs in the Horizon system, and that he could not be sure there were not more. It indicated that he must have known of the bugs earlier because he had informed the independent investigators Second Sight that they existed.
A few weeks later Mr Clarke wrote formal legal advice to the Post Office which warned that Mr Jenkins had failed to disclose information “in plain breach of his duty as an expert witness”, and this put the Post Office “in breach of its duty as a prosecutor”.
A lawyer for Mr Jenkins told the in March it would be “inappropriate” for him to comment ahead of him giving evidence to the Inquiry in June.
However, despite raising these doubts over Mr Jenkins’ testimony, Mr Clarke advised the Post Office that the information did not have to be disclosed to lawyers representing Mrs Misra.
That information would have allowed her to mount an “irresistible” appeal against her conviction, and would have helped defendants in other cases too, lawyers at the Inquiry suggested.
Mr Clarke said Post Office lawyers never showed him all the documents from the trial.
He said he had asked “on a number of occasions” to see the file of documents relating to the trial.
“I came to the conclusion that it was deliberately withheld from me,” he said.
He said he was “misled” by the Post Office over whether there were other Horizon bugs, too.
When he joined the Post Office in 2013, Mr Clarke said he asked for a copy of the Post Office’s prosecution policy – the rules they used to decide whether to proceed with prosecutions against sub-postmasters.
What came back was a “single A4 document, badly photocopied”, he told the Inquiry. “I can’t remember what it said, but it wasn’t a prosecution policy,” he said.
He proposed a revised version based on the Crown Prosecution Service’s policy, and was disappointed when what he called a “watered-down” version was adopted.
