He is Goldman Sachs' chief economist. That position - and O'Neill's reputation - makes him one of the world's most sought-after economic commentators. But his background is unusually modest for man with such professional influence.
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From there he went to Sheffield University to study geography and economics. He dropped the geography, concentrated on playing football and going to the pub, but still shone at economics.
It was also during these years that he developed a love for Manchester United, eventually becoming a non-executive director and investor in the club, prior to the takeover by the Glazer family in 2005.
O'Neill went public with his concerns about United's financial position earlier this year, at a time when the Glazer family were seeking new means to decrease the club's debt repayments.
"There's too much leverage going on with Manchester United," said O'Neill, who appeared to have been caught off-guard when quizzed on the bond issue by Zijing Wu, a Bloomberg reporter, at the end of an eight-minute interview on China's currency policy. "I value my long-term support for Manchester United better than anything else," he added. O'Neill's comments raised eyebrows because Goldman Sachs was among the advisers on the bond issue.