David Prosser: If the regulator fails to explain its role in RBS debacle its report will be a whitewash

Outlook Who should be most nervous about the publication on Monday, finally, of the Financial Services Authority's report into the collapse of Royal Bank of Scotland three years ago? The answer, though it may surprise you, is not the former executives of RBS, whose poor decisions brought one of the world's largest financial institutions to its knees. Rather it is senior officials at the regulator itself who have most to lose.

Is that why the FSA was so keen not to publish the results of its inquiry into RBS's failure? This report has had to be dragged out of the regulator, which claimed it had secured legally sensitive and commercially private information from the parties involved on the basis that it would be kept out of the public domain. Given that the story of how the FSA failed to intervene as RBS headed for the precipice is as big a part of this saga as the bank's own mis-steps, one has some suspicions about the regulator's motives.

The row over the FSA's determination to keep its deliberations private was prompted by its brief announcement, more than a year ago now, that it planned to take no further regulatory action against any individual at RBS. That left former head of investment banking Jonny Cameron as the only RBS executive to have been censured over the affair – and Sir Fred Goodwin and Sir Tom McKillop, the bank's former chief executive and chairman, in the clear.

Remarkably, however, those who have had access to drafts of the FSA report to be published next week say the work of those two men, who became poster boys for Britain's banking crisis, is not at its core. Only the regulator can explain why that is so.

Nor will it be the only question the FSA has to answer on Monday. If the regulator's report fails to explain how and why it failed to intervene when RBS shelled out £10bn for ABN Amro in the autumn of 2007, it will be a whitewash. This, after all, was a deal that undermined RBS's capital strength a full six months into a sub-prime lending crisis. The regulator appears not to have noticed the poor quality of the due diligence undertaken by RBS, which only a few months later had to make huge writedowns on the assets it had acquired and launch what was then the UK's largest ever rights issue.

What, moreover, will the report say about FSA chief executive Hector Sants, who was head of wholesale banking regulation at the time of the ABN deal? Mr Sants will shortly become a deputy Governor of the Bank of England (which, for that matter, isn't immune from criticism).

For many at the regulator, this is going to be a weekend of apprehension. On Monday morning the FSA's senior management team can expect to be attacked all over again for the failures of the financial crisis, or attacked for failing to address them.