The scale of the decision was summed up by a professor of politics, who said: "This is the biggest shock to European politics since the fall of the Berlin Wall." The vote has already led Britain's leader David Cameron to resign. He was leader of the campaign to stay part of the EU. He said the country needed "fresh leadership". Less certain is what will happen to the millions of non-British EU citizens living in Britain and the Britons living in other EU countries. Others may follow the UK's lead in exiting the EU. Politicians in Holland and France said: "Now it is our turn.