Conservative Prime Minister David Cameron holds his promised referendum on Britain's renegotiated European Union membership, hoping to capitalise on his personal popularity after a decisive May 2015 election victory and persuade Britons to stay in the bloc.
In February he sealed a deal with the EU that is more favourable to Britain. He argued for reform in areas including immigration, economic competitiveness and national sovereignty.
The prime minister outlined his reform wish list at an EU summit in Jun 2015 and negotiations continued until February.
The debate over leaving the bloc, dubbed Brexit, has divided Britons, who are split on whether the strategic benefits of bloc membership outweigh the costly bureaucracy and erosion of national sovereignty.
The issue has split the Cabinet and Parliament. It is expected that 13 junior ministers will back a British exit, along with some 150 Tory MPs.
Date written/update: 2016-02-22