Wall Street crises have consequences. By 1932, John Maynard Keynes viewed financiers as “subhuman” and “of gangster mentality”. In 1933, at his inauguration, President Franklin Roosevelt told America that “the money changers have fled from their high seats in the temple of our civilisation”. The next two years saw the Glass-Steagall Act, which split commercial and investment banking, and the birth of the Securities and Exchange Commission.

The severity of the fallout from today’s crisis partly depends on the scale of loss borne by the public sector. So far central banks can, just about, present their activity as that of lenders of the last resort: lending to banks (and now dealers) in return for good collateral. Even the UK Treasury says nationalised Northern Rock’s assets exceed its liabilities.