The Timetable of Britain's exit from EU

The first step towards leaving is the British government invoking Article 50 of the Treaty of Lisbon. This in itself is already causing problems as the Conservatives want to wait for a leadership election and a new prime minister by October – and the EU wants to get on with it now.

Once this is invoked, the remaining 27 states will discuss the withdrawal. Negotiations will begin between Britain and the EU and a draft agreement will then be put to the European Council. The deal needs approval from at least 20 countries that cover at least 65% of the EU’s population and then to be ratified by the European Parliament. The process can be extended beyond two years if all 27 countries agree. If not then the EU treaties cease to apply to the UK and it leaves the EU.

States will drive a hard bargain: EU Commission president Jean-Claude Juncker said ‘deserters won’t be treated with kid gloves’. Both French and German finance ministers have said the UK should not be allowed to remain in the single market: ‘out is out.’ It is thought EU leaders will be keen to avoid any contagion and fear the breaking apart of the EU project.

Many experts say delaying article 50 will be negative for the markets. “While there is uncertainty about whether negotiations are taking place and with whom, it’s not good for the UK,” said London School of Economics professor of EU law Damian Chalmers.