EU leaders have agreed a deal in Brussels which will pave the way for an in/out referendum in the UK before the summer.
The development came late on the second day of gruelling talks in Brussels between leaders of the 28 member-states, which saw the Prime Minister face opposition to proposals to restrict migrant benefits and provide new protections for countries outside the single currency.
Lithuanian president Dalia Grybauskaite broke the news in a tweet from the round-table discussions: "Agreement #UKinEU done. Drama over." And Danish PM Lars Lokke Rasmussen said: "David Cameron fought hard for Britain. Good deal for UK and for EU. Congrats!"
And minutes later, the breakthrough was officially confirmed by European Council president Donald Tusk, who said: "Deal. Unanimous support for new settlement for UK in EU."
The agreement clears the way for David Cameron to return immediately to London and call a special Cabinet meeting on Saturday to endorse the deal and set a date for the long-awaited referendum - widely expected to come on June 23.