A couple of weeks ago, a group called the “Patriotic Millionaires” turned up at Davos to advocate something rather unusual – they wanted to pay higher taxes. Led by the granddaughter of Walt Disney, they asked governments to consider taxing the very rich more on their assets. Taxing wealth, rather than income, has surged onto the political agenda on both sides of the Atlantic. US Senators Bernie Sanders and Elizabeth Warren had run for the Presidency with plans to annually tax the wealth of...