I’m due to debate the philosopher A.C. Grayling on Saturday about whether there should be a second EU referendum on the terms of the Brexit deal. It is part of a two-day event being held at Central Hall, Westminster, on ‘Brexit and the political crash’. It is billed as a ‘convention’, an opportunity for all sides in this debate to discuss Britain’s future, but the reference to the ‘political crash’ is a giveaway.