Royal Bank of Scotland on Thursday lost a court battle to withhold transcripts, notes and interview records from thousands of retail investors suing the bank over an ill-fated, £12 billion ($15 billion) share sale in 2008. The bank is being sued by a group of 27,000 retail investors, who hope the information will bolster their case ahead of a trial next March.

The bank attempted to settle the lawsuit with an £800Mn pound out-of-court deal on Monday. But only institutional investors accepted the offer, dropping their part of a claim that alleges the bank misrepresented its parlous financial state when asking investors to stump up cash in 2008.

Shareholders lost around 80% of their investments after the bank's near collapse, just months after the cash call. RBS was rescued by a £45 billion taxpayer-funded bailout at the height of the credit crisis.

In the case, Judge Robert Hildyard rejected an attempt by RBS to class the documents as legally privileged and confidential, noting: "I accept that the court has discretion to prevent disclosure and inspection, or impose conditions, in an exceptional case ... But I have not been persuaded that this is such a case."