The most significant announcement David Cameron made this morning was not that he plans to resign in October. It was that he will not be triggering article 50 of the Lisbon treaty in the meantime. When to “start the formal and legal process of leaving the EU” would be a matter for the new prime minister, he said.

After this vote the UK is diminished, our politics poisoned | Gary Younge Read more

So by sacrificing his own job, Cameron has bought Britain three months’ breathing space. He had told MPs in February that, in the event of a Brexit vote, the British people would “rightly expect” him to trigger article 50 “straight away”.

In the meantime, everything continues exactly as before. The referendum vote has immense political implications but no direct legal effect. We remain in the EU.

Of course, the new prime minister will be expected to respect the result of the referendum and, in due course, to notify the European council – which includes all EU heads of state or government – of the UK’s intention to withdraw from the EU under article 50. But we now have three months in which EU leaders can devise some sort of associate membership for the UK that just might be enough to stop that happening.

And even if the government is led by Boris Johnson and/or Michael Gove, the new prime minister would probably want to take some time before giving notice to quit the EU. That is because article 50 is a wasting asset with no emergency brake. There is nothing in the Lisbon treaty that allows a leaving state to change its mind and stop the process – although that result could no doubt be achieved by treaty amendment if the other 27 EU states agreed to support it.

So I would expect the UK’s negotiations with Brussels – ahead of an article 50 notification – to continue into next year. If there is a significantly better deal on offer, the new prime minister might choose to put it to the people – not, I suspect, by holding another referendum but by calling an early general election.

The Fixed-term Parliaments Act 2011 allows for this in two possible ways. One would require the support of two-thirds of the House of Commons. The other can be done by passing a vote of confidence on a simple majority – but this method includes a cooling-off period of 14 days to allow time for a new government to be formed and win MPs’ support.

Article 50 says that a member state “may decide to withdraw from the [EU] in accordance with its own constitutional requirements”. Those requirements are, of course, a matter for the UK. But exactly what they are, in the absence of a codified constitution, must be open to doubt.

Before the referendum result was declared, most MPs had opposed Brexit. Some of them will now feel it is their duty to give effect to the majority decision of the voters. But since it will be at least three months and probably a lot longer before the new prime minister is in a position to trigger article 50, my own view is that the government will require, at the very least, a majority vote in the House of Commons before proceeding.

The Cameron Conservatives era is over. The party now belongs to the Brexiters | Matthew d’Ancona Read more

One might have argued that a kamikaze prime minister could have triggered article 50 immediately after the referendum result was declared, using his prerogative powers. Those powers are used to sign treaties but not, I would argue, to put them into effect in the UK. In any event, there is a growing constitutional convention that prerogative powers are subject to parliamentary approval, as we saw with the Commons vote in August 2013 against air strikes on Syria.

There has been some talk of enacting UK legislation, ahead of the article 50 process, with the aim of limiting the powers of the EU or its court of justice. But that would put the UK in breach of its treaty obligations under international law and there is every chance that such a move would be blocked in parliament.

Article 50 is sometimes described as a two-year process. That’s an oversimplification.

The two years do not include the period leading up to a notification, which could easily be a year or more. The negotiations can continue for more than two years with the agreement of all other EU states. And it would be open to the UK and the EU to agree a date for withdrawal that is earlier than two years after the trigger date – or, indeed, later.

What is clear, though, is that any EU state could insist that the UK leaves two years after the date it lodges its notification under article 50 – regardless of the state of negotiations. That is why triggering withdrawal is such an important decision. The UK could apply to rejoin the EU in the same way as a new member, but Brussels could then lay down conditions – such as joining the euro or the Schengen free-movement zone – that would be regarded as unacceptable.

In summary, then, withdrawal from the EU will be far from immediate. The longer it takes to negotiate a deal, the more opportunity there is for the terms of the UK’s new relationship with the EU to change.

Subject to that, though, parliament is now facing the huge task of extricating the UK from EU law. Lord Lisvane, the former clerk to the House of Commons, has pointed out that it is not as simple as repealing the European Communities Act 1972, under which the UK joined what is now the EU.

There is a vast swath of EU-inspired secondary legislation in place, much of which we might want to keep in some form or another. The civil service will need many more officials and lawyers to work out what to do.

Any legislative changes will require parliamentary approval, which is why it is so important for the new prime minister to command a majority in parliament committed to the task of taking the UK out of the EU. Buyers’ remorse is not out of the question.