A European Union flag is held in front of the Big Ben clock tower in Parliament Square, central London, Britain July 2, 2016. REUTERS/Paul Hackett/File Photo

A European Union flag is held in front of the Big Ben clock tower in Parliament Square, central London, Britain July 2, 2016. REUTERS/Paul Hackett/File Photo

A European Union flag is held in front of the Big Ben clock tower in Parliament Square, central London, Britain July 2, 2016. REUTERS/Paul Hackett/File Photo

July 20, 2016 2:56 AM (UTC+8)