Yesterday journalists from 78 countries started publishing stories exposing the hidden wealth of national leaders, state officials and others, based on 11.5m documents leaked from the database of a Panamanian law firm, Mossack Fonseca. These papers contain details of secretive offshore structures used by Mossack’s clients. The anonymous firms’ activities appear to range from the perfectly legitimate to the deeply dodgy, including the looting of public wealth. (Mossack says it has never been charged with wrongdoing and conducts thorough due diligence.) More revelations are expected this week.