Professor Richard Rose from the UK: Delaying the countdown to Brexit - a cost-benefit analysis

The referendum question was simple but the outcome has produced a sequence of conundrums. The most immediate question – when should the UK formally notify the EU it will leave – has a simple answer in the abstract: When it is ready. It is also strategically critical, because doing so starts a 24-month countdown until the UK ceases to have any rights or obligations of membership. 

The British government wants to retain a maximum of rights to trade in the single market and a minimum of obligations to accept EU immigrants. The EU will only begin discussing its position once Brexit is officially triggered.