Christine Lagarde ought to be a happy woman. As she noted in a speech in Hong Kong last week, there is good economic news around the world. The US is operating at full employment, the upswing in Europe has spread across the continent, Japan is growing strongly and the outlook for Asia is bright. All the same, Lagarde has plenty to worry about as she prepares for this week’s half-yearly meeting of the International Monetary Fund, the organisation run by the former French finance minister.