In the confused aftermath of the Brexit Referendum in June 2016, the historic decision was framed insightfully by John Lanchester as a classic example of the ‘Overton window’: ‘The Overton window is a term from political science meaning the acceptable range of political thought in a culture at a given moment. British politics has never seen a purer example of the Overton window than the referendum on membership of the EU. In 1994, the billionaire James Goldsmith founded a political party whose sole purpose was to advocate for a referendum. The Referendum Party was a long, long way outside the…