Channel 4 News has obtained covert recordings, dating back to 2013, where forensic accountants from Second Sight describe how the Post Office and Fujitsu knew their IT system could change subpostmasters' accounts.
Lord James Arbuthnot, the Conservative MP who campaigned for justice for subpostmasters, was shown in the C4 footage and appeared emotional when he gave his response.
(Credit: Channel 4 News)