Cameron's voice breaks during emotional resignation speechPlay!
While England voted overwhelmingly for Brexit, Scotland and Northern Ireland backed Remain. Statements are expected to be made by Sinn Fein and the SNP later today calling for a breakaway from the Union. London backed Remain but the turnout was lower than expected because of bad weather.
Meanwhile on the market, the FTSE 250 index has plunged a whopping 11.7pc. The index of so-called mid-cap companies had dropped an astonishing 2,017 points to 15,309 in the first few minutes of trading.
Jean-Luc Mélenchon, French firebrand leftist MEP, said that France would have voted to the leave the EU if asked. "This is the end of a world that begins with this Brexit," he told France Info radio.
"This teaches a lesson to the whole of Europe - either we change it or we leave it. This is the time for a plan B."
He described the current EU as "dead, killed by privileges for the cast of Eurocrats, by permanent lies, by the politics of flexibility...Everyone has had enough."
He said that already the "five president of the EU" had started "the process of drawing up a new (EU) treaty".
"Once again, they are doing so in hiding. Once again leaders are not talking. I fear a domino effect."
"The daily reality of Europe doesn't correspond at all to what the EU tried to start 30 years ago at least. Germany must stop ceaselessly telling other peoples what's best for them. France must have some willpower and make proposals. It's not that much to ask to live ones life working and being paid in a dignified way, receiving healthcare and education. All this is cast into question with the EU."
Donald Tusk, the president of the European Council, has appealed for calm and says the must be no "hysteria" about the British result.
There will be "no legal vacuum" and EU law will continue to apply until Britain formally leave.
There are serious "political consequences" for the UK but leaders are "prepared".
In a statement he says: "I would also like to reassure you that there will be no legal vacuum. Until the United Kingdom formally leaves the European Union, EU law will continue to apply to and within the UK.
Donald Tusk, the president of the European Council CREDIT: LAURENT DUBRULE
"There's no hiding the fact that we wanted a different outcome of yesterday's referendum. I am fully aware of how serious, or even dramatic, this moment is politically. And there's no way of predicting all the political consequences of this event, especially for the UK.
"But this is not a moment for hysterical reactions. I want to reassure everyone that we are prepared also for this negative scenario. As you know the EU is not only a fair-weather project. "Over the past two days I have spoken to all the EU leaders, I mean Prime Ministers and Presidents as well as heads of the EU institutions, about the possibility of a Brexit. Today, on behalf of the twenty seven leaders I can say that we are determined to keep our unity as twenty seven.
"For all of us, the Union is the framework for our common future. I would also like to reassure you that there will be no legal vacuum. Until the United Kingdom formally leaves the European Union, EU law will continue to apply to and within the UK. "All the procedures for the withdrawal of the UK from the EU are clear and set out in the Treaties. In order to discuss the details of further proceedings, I have offered the leaders an informal meeting of the twenty seven in the margins of the European Council summit. And I will also propose to the leaders that we start a wider reflection on the future of our Union. "Finally, it's true that the past years have been the most difficult ones in the history of our Union. But I always remember what my Father used to tell me: What doesn't kill you, makes you stronger."