Warren Buffett is notoriously immune to the charms of investment bankers, but there is one of whom he speaks highly. Byron Trott, head of Goldman Sachs's Chicago office, is thought to have helped to persuade the Sage of Omaha to take a $5 billion stake in the bank, despite his traumatic experience in banking with Salomon Brothers in the 1990s.

This year Mr Buffett said: “Byron is the rare investment banker who puts himself in his client's shoes ... I trust him completely.”

He had already garlanded Mr Trott, 49, vice-chairman of investment banking at Goldmans, with praise in the 2003 annual report of Berkshire Hathaway, his investment company: “Byron ... understands Berkshire far better than any investment banker with whom we have talked and - it hurts me to say this - earns his fee.”

This is in contrast to Mr Buffett's public criticism of much of Wall Street for causing the present financial crisis. “Wall Street is going to go where the money is and not worry about consequences,” he has said.

This week is not the first time that Mr Trott has brought the veteran investor to the table during his 25 years at Goldman. Their association began in 2002, when he helped Mr Buffett to pull off a deal for Berkshire to borrow money at negative interest. Since then, he has been instrumental in bringing Mr Buffett into Mars's $23 billion acquisition of Wrigley and has advised on the purchase of McLane, a grocery distributor, from Wal-Mart.

Little is known about Mr Trott's personal life, as he is rarely interviewed, although he appears to have donated money to both Barack Obama and John McCain, the US presidential candidates.

Mr Trott started at Goldman as a broker in 1982 before making the unusual move into investment banking in 1988, where he served under Henry Paulson, then managing partner of the Chicago office.

He became a partner in the record year of 1994, when 58 up-and-coming young bankers were made partners at Goldmans, and is one of few surviving partners from the era before the bank's initial public offering.