After a year of tussles with lawyers, politicians and bankers, the Financial Services Authority will finally publish its report into the near-collapse of Royal Bank of Scotland on Monday.
The 450-page report, released at 6am, will be the FSA's second act of self-flagellation after it took the blame for the Northern Rock crisis. Lord Turner, the watchdog's chairman, has made it clear the regulator's failings in overseeing RBS will form a major part of the tome.
Central to the judgement will be RBS's disastrous takeover of ABN Amro as the credit crunch gathered steam. The bank went ahead with the deal, waved through by the FSA, as markets froze.
The Dutch bank increased its exposure to toxic US sub-prime assets and bad loans made to companies. After battling for most of 2008 to stay afloat, RBS was on the verge of collapse before the Government part-nationalised it, spending £45 billion on an 83 per cent stake.
Lord Turner set the tone for the report in June when he admitted the FSA committed "insufficient resources" to large, systemically important banks. The watchdog will produce a "most open, self-critical report", he added.
That was not the case a year ago when the FSA published its first version. The single-page document, which said it had found evidence of mistakes but no wrongdoing, was ridiculed and politicians put pressure on Lord Turner to pledge a fuller account.
In May the Treasury Committee took control of the report by imposing its own City grandee examiners, Bill Knight and Sir David Walker. Their job was to make sure the final report was an accurate reflection of the thousands of pages of evidence submitted.
RBS, which was the biggest in the world by assets before its near-implosion, will also face sharp criticism. Lord Turner will use withering words about RBS's checks on the books of ABN Amro.
He is said to have insisted on describing RBS's due diligence on ABN Amro as "two lever-arch files and a CD-ROM" – despite objections raised by lawyers representing former executives.
Sir Fred Goodwin, RBS's former chief executive, told analysts at the time that RBS would do "due diligence light" on ABN Amro but that this would be sufficient because Barclays, which competed with RBS to buy the bank, had already looked at the books and ABN Amro was regulated around the world.
Disputes over confidentiality have delayed the report because the FSA is not allowed to release information about people gathered from its investigations without their permission. Johnny Cameron, RBS's former head of investment banking, is said to receive the toughest criticism.
A City lawyer said yesterday: "The sort of growth programme they had [the ABN Amro deal] prior to things going wrong, you wouldn't have done that without talking to your regulator."
The FSA has argued that it was not its job to veto the ABN Amro deal. The report may call for explicit powers to block risky mergers and the ability to prosecute bank executives for incompetence.