Theresa May, William Hague and others say that the EU will not want to trap Britain in the backstop because it is not in its interest. It will want to move to a free-trade agreement for its own benefit. If that is so, why is the backstop the thing above all others upon which the EU insists? Brexiteers must absolutely oppose the backstop because agreeing it would repeat Britain’s delusion in every European negotiation over nearly 50 years, which is that we should grab ‘practical’ advantages and concede ‘windy’ principles.