For the final three years of his 18-year career at Goldman Sachs, Jim O’Neill, the Treasury’s new commercial secretary with responsibility for developing the Northern Powerhouse, served as chairman of Goldman Sachs Asset Management, the company’s least-regarded and most bothersome unit. While two younger executives ran the business, O’Neill was dispatched to faraway conferences to bore audiences of docile suits with his views on whether Nigeria or Malaysia offered a better investment opportunity.