No governance failure at Royal Bank of Scotland? That's what the Financial Services Authority claimed last week to widespread incredulity. Now FSA chairman Adair Turner has more explaining to do. As we report , Sir Philip Hampton, chairman of RBS, appeared to come to the opposite conclusion after nine months' examination of the wreck.

Hampton thought his predecessors on the RBS board failed to live up to their "fiduciary duties" and did not conduct adequate due diligence before buying part of ABN Amro in 2007. His comments, in a meeting with three US politicians, were relayed in a cable sent from the US embassy in London.

Hampton is free to challenge this report of his conversation. But, if the cable is a correct summary of his remarks and views, one must assume he would dispute Turner's claim last week that the RBS board's poor decisions "were not … made without consideration of relevant information".

Who's right? There's only one way to settle the question – make the regulator publish the findings of its investigation into the events leading up to the near-death of RBS. Turner last week offered various explanations for why publication is not possible. The FSA thinks the law doesn't allow publication where no enforcement action is triggered, and no easy-to-publish report exists. But there seems to be nothing to prevent parliament or the government from ordering the FSA to revisit the issue, conducting a fresh investigation if necessary, with the aim of producing an official report.

Even before the WikiLeaks revelations, the FSA's 12-sentence summary of its investigation looked too thin to stand as the last words on events at RBS. Now the case for further investigation and publication is overwhelming: there is a serious question mark over one of the FSA's main findings.