June 23 is a date looming large in the diaries of U.K. voters. For only the second time since the 1970s, they will have the chance to vote on the United Kingdom’s position in the European Union. The referendum on whether the United Kingdom should remain in the European Union follows a period of negotiations in which the U.K. government sought to secure a range of concessions to appease a large proportion of voters who seek a fully independent United Kingdom.

The government of Prime Minister David Cameron secured concessions from the rest of the European Union, including protection from potentially anticompetitive rule-making favoring other European states; lower social security payments to migrants for children living overseas; and payment of social security for new migrants, which would be phased in over a period of four years.

For many voters, these concessions were not enough. Many individuals, businesses and politicians, including London Mayor Boris Johnson and o