Factbox: How will Britain's EU membership referendum work?

Prime Minister David Cameron has said a referendum on Britain's membership of the European Union will be held on June 23. Like with a parliamentary election, British, Irish and Commonwealth citizens aged over 18 who live in Britain, and British nationals who have lived overseas for less than 15 years will be allowed to vote in the EU referendum. In addition, members of parliament's upper house and citizens of Gibraltar who are eligible to vote in European Parliamentary elections will also be abl