Theresa May has agreed to a Halloween Brexit deadline after EU leaders offered to delay the UK’s departure until October 31 following hours of talks at a crunch summit.
The new timeline was a compromise solution thrashed out over five hours of discussions in Mrs May’s absence after French President Emmanuel Macron held out against a longer delay.
Most of the leaders at the Brussels summit are understood to have favoured the longer extension of as much as a year recommended by European Council President Donald Tusk.
But Mr Macron dug his heels in for a shorter delay, warning that a no-deal Brexit would be less damaging than a disruptive UK remaining for month after month.
Mr Tusk urged that the agreed extension was "flexible".
Irish Taoiseach Leo Varadkar said the UK must now hold European elections in May, or leave on 1 June without a deal.
Speaking at a press conference after the six-month delay was announced, Mr Tusk issued a stark warning the UK, saying: “please do not waste this time”.
He added: “This extension is as flexible as I expected, and a little shorter than I expected, but it is still enough to find the best possible solution.”
Mrs May told a separate conference: “I know that there is huge frustration from many people that I had to request this extension.
“The UK should have left the EU by now and I sincerely regret the fact that I have not yet been able to persuade Parliament to approve a deal which would allow the UK to leave in a smooth and orderly way.
“But the choices we now face are stark and the timetable is clear.”
She added that the extension would be until the end of October "at the latest".
"I continue to believe we need to leave the EU with a deal as soon as possible," Mrs May said.
"And vitally the EU have agreed that the extension can be terminated when the Withdrawal Agreement has been ratified, which was my key request of my fellow leaders.
"For example, this means that if we are able to pass a deal in the first three weeks of May, we will not have to take part in European elections and will officially leave the EU on Saturday June 1."
Mrs May continued: "During the course of the extension the European Council is clear that the UK will continue to hold full membership rights, as well as its obligations.
"As I said in the room tonight there is only a single tier of EU membership, with no conditionality attached beyond existing treaty obligations."
Maltese Prime Minister Joseph Muscat welcomed the compromise date, saying: "A Brexit extension until 31 October is sensible since it gives time to UK to finally choose its way.
"The review in June will allow the European Council to take stock of the situation."
It is understood the June review will assess UK co-operation during and after May's European elections, with the possibility of the exit date being brought forward to the PM's preferred date of June 30.
Mrs May gave a one-hour presentation setting out her case for an extension to June 30, with a break clause allowing the UK to leave as soon as her Withdrawal Agreement was ratified.
But she had to leave the EU27 to discuss the UK's future in her absence over a dinner of scallop soup and loin of cod. It took five hours of wrangling before she was summoned back from the residence of UK ambassador Sir Tim Barrow for her agreement to be sought.
Failure to reach unanimous agreement would have meant the UK would crash out of the EU without a deal at 11pm on Friday.
