Prime minister David Cameron has confirmed his intention to resign as prime minister, after Britain made the historic decision to leave the European Union.
The Brexit campaign secured victory with 52% of the vote after a night of high drama, in which England and Wales backed leaving the EU while London, Scotland and Northern Ireland voted in favour of staying in.
In an emotional statement outside Downing Street, Cameron said he would stand down in time for the Conservative conference in October, but promised to "steady the ship" over the next three months.
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"I was absolutely clear about my belief that Britain is stronger, safer and better off inside the European Union," he said. "And I made clear the referendum was about this and this alone, not the future of any single politician, including myself. But the British people have made a very clear decision to take a different path and as such I think the country requires fresh leadership to take it in this direction.
"I will do everything I can as prime minister to steady the ship over the coming weeks and months. But I do not think it would be right for me to try to be the captain that steers our country to its next destination.
"This is not a decision I have taken lightly. But I do believe it’s in the national interest to have a period of stability and then the new leadership required.
"There is no need for a precise timetable today. But in my view we should aim to have a new prime minister in place by the start of the Conservative party conference in October."
The prime minister, who fought back tears as he discussed the legacy of the coalition and Conservative governments he has led, concluded by saying: “I love this country and I feel honoured to have served it and I will do everything I can in the future to help this great country succeed”.
The value of the pound tumbled dramatically in the wake of the vote, while the FTSE 100 index fell by more than 500 points, its biggest one-day fall since the height of the global financial crisis in 2008.
Just after Cameron spoke, governor of the Bank of England Mark Carney gave a statement in a bid to reassure markets, saying the UK was "well prepared", and confirming that the Treasury had been involved in "extensive contingency planning" in the event of Brexit.
Carney said the UK's central bank would "not hesitate to take additional measures as required as markets adjust" in the wake of Britain's decision to quit the EU.
Cabinet is set to meet on Monday to discuss the government's response to the vote, as the civil service braces for a protracted – and potentially all-consuming – withdrawal process.
Former cabinet secretary Lord O'Donnell, who led the civil service until 2011, said the government's first priority would be to work out when to trigger Article 50 of the Lisbon Treaty, which notifies the European Council that the UK intends to withdraw and opens a two-year window for talks on the terms of exit.
O'Donnell told the BBC: "If I were cabinet secretary I would be saying there is no great rush about that, because this is a two-year process – and believe me this is not a simple process. It was designed to make leaving very difficult for the leaving country."
No country has yet had cause to invoke Article 50, and the former head of the civil service pointed out that it had taken Greenland, which left the European Economic Community (EEC) in 1985, three years to "sort out" its own departure, despite having a small population.