Two key witnesses due to give evidence before the Post Office Inquiry this week have had their appearances postponed after yet another disclosure failure.

The Post Office contacted the inquiry and core participants to admit a problem with locating approximately 363,000 emails which were moved across to a different system in 2012.

Potentially hundreds of relevant documents have either not been disclosed or have yet to be assessed by lawyers for the inquiry. The inquiry heard today that the process would not be completed in time for this week’s evidence sessions with former Post Office investigators Stephen Bradshaw and Dave Posnett, resulting in both appearances being postponed. At least two victims of the Post Office scandal had travelled to London and stayed overnight to hear Bradshaw’s evidence in person.

This is the latest disclosure issue to hit the inquiry. The evidence of Gareth Jenkins, a former Fujitsu engineer, was postponed over the summer because documents had not been shared in time. Jenkins’ four-day appearance is now scheduled to begin on 30 November.

In July, inquiry chair Sir Wyn Williams directed that all future requests for evidence would carry a notice under section 21 of the Inquiries Act 2005 which carries a threat of criminal sanction.

The latest problem was caused by the transfer of data from a Microsoft Exchange server which has prevented the Post Office from being able to locate relevant emails.

An email was sent by Post Office lawyers late last Friday evening alerting the inquiry to the issue and disclosing 421 documents which had to be read over the weekend. The current position was confirmed at 11.14pm last night.

Kate Gallefant KC, for the Post Office, said the organisation ‘deeply regrets’ that it had not been able to disclose documents in time for witnesses’ appearances. She said this was caused by technical faults rather than any lack of willingness to be transparent but conceded that a ‘significant number’ of potentially relevant documents had yet to be disclosed.

Christopher Jacobs, for some of the victims of the scandal, said there ‘seemed to be a pattern’ where the Post Office had admitted late in the day that disclosure was not possible. ‘Our clients say this is simply not good enough and would ask whether the inquiry can impose a mechanism on the Post Office to prevent what they see as abuses,’ said Jacobs. ‘The perception from our client group is that the Post Office is seeking to control these proceedings through the disclosure process.’

Jason Beer KC, counsel for the inquiry, said the conduct of the Post Office was ‘standing in the way’ of the process and that contemporaneous emails of the type not yet disclosed had previously provided a ‘rich seam’ of evidence for cross-examining witnesses who otherwise said they could not recall what had happened.

The Bradshaw and Posnett evidence sessions were postponed to a later date, with a decision yet to be made on witnesses due to appear next week. Lawyer Teresa Williamson is still scheduled to appear on Wednesday.