2016 United Kingdom European Union membership referendum (Brexit referendum)

Question, electorate and conduct

The referendum posed a single-choice question with two options: Remain a member of the EU or Leave the EU. The franchise included UK citizens resident in the UK, qualifying Commonwealth citizens, citizens of the Republic of Ireland resident in the UK, and eligible residents of Gibraltar. The poll was administered by local returning officers; campaigning included televised debates, print and online advertising, and public events. Observers highlighted the role of social media in shaping public debate.

Campaign themes and participants

Campaigning was dominated by two broad camps. Supporters of Remain emphasised economic risks, market access and stability, while Leave advocates stressed national sovereignty, control over immigration, and the ability to make laws without EU institutions. Political parties and major public figures were divided: some Conservative ministers campaigned on both sides, the then Prime Minister David Cameron backed Remain, while a number of leading Conservatives and other politicians supported Leave.

Immediate aftermath

Following the announcement of the result, the sitting Prime Minister resigned and a leadership change followed: David Cameron stepped down and was succeeded by Theresa May. The referendum was legally advisory rather than automatically binding, but its political impact compelled the government to begin the formal process of withdrawing from the EU, invoking Article 50 of the EU treaties to start negotiations.

Legal effects, negotiations and final outcome

The vote set in motion a multi-year negotiating process between the UK and the EU over withdrawal terms, future relationships, and transition arrangements. That process reshaped domestic politics, produced legislation to implement withdrawal, and culminated in the UK leaving the EU after extensive negotiations and parliamentary debates. The referendum therefore stands as a pivotal decision that changed the UK's constitutional and international position.

Significance and legacy

Beyond the immediate political turnover, the referendum had lasting effects on party alignments, regional politics (notably in Scotland, Northern Ireland and Gibraltar), public discourse on migration and sovereignty, and the terms of trade and cooperation with Europe. It remains a reference point for debates about direct democracy, national self-determination, and the complexities of disentangling long-standing political and economic integration.

• Date: 23 June 2016
• Question: Remain or Leave the European Union
• Result: 51.9% Leave
• Notable political change: resignation of David Cameron, succession by Theresa May