(FILES) In this file photo taken on February 20, 2016 British Prime Minister David Cameron leaves after delivering a press conference on February 19, 2016, at a European Union (EU) summit in Brussels, after reaching a deal with European leaders on his reforms. The deal, sealed after hours of haggling at a marathon summit, paves the way for a referendum on whether Britain will stay in the EU. The European Union's two top figures, Donald Tusk and Jean-Claude Juncker, presented its 28 leaders with draft proposals at a long-delayed dinner after hours of painstaking face-to-face talks on an issue that threatened place in the union. AFP PHOTO / JOHN THYS - Severing a truculent partnership stretching back five decades, Britain finally went its own way late Thursday four-and-a-half years after its shock referendum verdict in favour of divorcing the EU. Brexit became reality as Big Ben struck 11:00 pm (2300 GMT) in central London, just as most of the European mainland ushered in 2021 at midnight. (Photo by JOHN THYS / AFP)