David Cameron hailed his historic EU re-negotiation deal, declaring that he has secured Britain's "special status" in the 28 nation bloc.
At the end of marathon talks in Brussels, the Prime Minister said he had achieved his negotiating aims and would be recommending the agreement to the British people in a referendum now expected to be held on June 23.
"This deal has delivered on the commitments I made at the beginning of this re-negotiation process. Britain will be permanently out of 'ever closer union', never part of a European superstate," he said.
"I believe that this is enough for me to recommend that the United Kingdom remains in the European Union."
After finally securing the backing of the other 27 EU leaders for his plan, Mr Cameron was heading back to London to brief senior ministers at a Saturday morning meeting of the Cabinet at No 10.