Cairns faces up to seven years' jail if he is convicted on a charge of perjury.
The Herald last week revealed that the Metropolitan Police investigating the case contacted their New Zealand counterparts about a potential trial witness, Black Caps skipper Brendon McCullum, being undermined by material in the possession of Cairns.
A photograph of Cairns - taken shortly after the Herald broke the news of the charge against him - shows him carrying a clear plastic folder titled "BMC" and the names of McCullum and Kerry Schwalger (see below).
McCullum was then forced to swear an affidavit about his former professional relationship with Schwalger, his former mental skills coach, as part of a High Court injunction to stop a Sunday newspaper from publishing the information.
His lawyer, Garth Gallaway, said McCullum's resolve was "stronger than ever" and the episode also led New Zealand Cricket boss David White to issue a statement supporting his national skipper.
McCullum is likely to be a key witness against Cairns. However, it is possible the material could be aired at trial if the perjury case goes ahead.
The credibility of other witnesses, such as confessed match-fixer Lou Vincent, is also likely to be challenged by Cairns' legal team.
Up to a dozen former New Zealand representatives could be called as witnesses.
Cairns has denied any wrongdoing and said the perjury trial would give "an opportunity to face my accusers in an open forum ... so that I can clear my name once and for all".