Theresa May has been back in Brussels to attend a meeting of EU leaders, a day after surviving a leadership challenge at home. Her mission: to try to extract some form of concession from the other 27 EU member states that might persuade MPs in Westminster to support the withdrawal agreement the UK has concluded with the EU. Few commentators give her much chance of success. It still seems likely that when the deal is finally voted on by Parliament, it will be rejected. So what would happen then? Would the UK be heading for the EU exit door with no-deal? Might there be a vote of confidence that could lead to a general election? Could MPs from both main parties form a temporary government of national unity? Or might the Prime Minister accede to demands for a new referendum? With the historian Peter Hennessy, Jill Rutter of the Institute For Government, Agata Gostynska-Jakubowska of the Centre for European Reform and Meg Russell from University College London.