The proportion of wealth owned by a super-rich elite continues to grow in societies around the world. The glaring disparity between the 'have-mosts' and the 'have-nothings' has fuelled a wave of political anger. Stephen Sackur speaks to the former newspaper columnist, editor, and one-time high society hostess Barbara Amiel, whose recent memoir, wittingly or not, paints an extraordinary, even grotesque, picture of the lives of the wealthy.