LONDON, ENGLAND - MAY 28: Yanis Varoufakis, former finance minister of Greece, attends a Diem25 event at The UCL, Institute of Education on May 28, 2016 in London, England. Left-wing politicians and thinkers were today campaigning at the DiEM25 event to stay in the European Union ahead of the EU referendum on the 23rd of June. (Photo by Jack Taylor/Getty Images)