Britain’s financial and corporate governance regulators have told external audit firms to be more skeptical, claiming they let down investors, regulators, and “society at large” by failing to challenge management in the run-up to the financial crisis.

A joint paper from the Financial Services Authority and the Financial Reporting Council also called on audit firms to do more to help regulators. Among a series of ideas, it suggests that firms should blow the whistle to regulators if they find internal control weaknesses, for example.