David Cameron has announced he is to resign as Prime Minister after the UK voted to leave the European Union.
Speaking after Britain voted in favour of Brexit, he said the "will of the British people'' must be respected and it was an "instruction which must be delivered''.
He said there should be a new leader in place by the start of the Conservative Party conference in October.
He added: "I love this country and I feel honoured to have served it.''
His statement followed a remarkable night in which British people voted to leave the European Union after a nearly half a century of membership plunging the country into unchartered political and economic territory
With all the results declared, voters backed Brexit by a margin of 52 to 48 per cent.
The outcome is also likely to spark a second independence referendum in Scotland that, unlike England and Wales, voted to remain in the EU.
Nicola Sturgeon said it the vote in Scotland "made clear" that it saw its future as part of the European Union.
Markets reacted with alarm to the vote with the pound plunging against the dollar to levels not seen in more than thirty years. The FTSE was predicted to fall by around ten per cent.
One city analyst described the vote as "one of the biggest market shocks of all time".
The former Liberal Democrat leader tweeted "God help our country". The German Finance Minister Wolfgang Schäuble said it was a "sad day for Europe".
But Gisela Stuart, the Labour chairwoman of Vote Leave, called for calm.
"In the long run both Europe and the United Kingdom will emerge stronger as a result," she said.
The unofficial result was confirmed just after 4.40am in the morning after a surge in support for leaving the EU confounded predictions made just hours before polls closed.
Middle England joined forces with the country’s industrial heartlands of the North East and North West to comprehensively reject warnings of economic Armageddon and vote to leave.
Support for remain was strongest in London and Scotland but with cities like Sheffield and Birmingham joining with Canterbury, Torbay and Peterborough in favour of Brexit momentum drifted away from the remain camp.
The result will now trigger a formal process of British withdrawal from the European Union. A planned meeting of European leaders next week in Brussels will now become an emergency Brexit summit.
