Richard Fuld, the chief executive of Lehman Brothers, had reason to feel confident after leaving a dinner with Hank Paulson, the Treasury secretary, in April 2008.

In an e-mail to his chief legal officer, Mr Fuld said that Mr Paulson, the former chief executive of Goldman Sachs, had a “worried view” about Merrill Lynch but that Lehman had a “huge brand” with the US Treasury.