Ten Years After the Brexit Referendum: How Leaving the EU Reshaped the UK

On 23 June 2016, about 51.9% of British voters — close to 17 million people — voted in a referendum to leave the European Union (EU), the world's largest single market. The separation was completed in 2020 with the Trade and Cooperation Agreement governing post-Brexit trade and security ties between the UK and the EU. A decade on, the consequences are being widely assessed.

Supporters had argued that Brexit would restore sovereignty, control immigration and bring prosperity. Instead, the UK has seen political instability, slow economic growth and rising inflation. The period after the referendum saw six prime ministers leave office without completing a full term — the latest being Keir Starmer, who resigned on the eve of Brexit's 10th anniversary despite a large 2024 election majority.

Leaving the EU single market and customs union created non-tariff barriers such as extra paperwork and customs procedures, which hurt small UK businesses and trade. Politically, support for the two traditional parties has fallen to record lows, while populist forces — the anti-immigrant Reform UK and the eco-populist Greens — have gained ground. Brexit also strained the union itself, with pro-independence sentiment rising in Scotland and Northern Ireland, which had voted to remain.

For aspirants, Brexit is a key International Relations topic. Important points are the 2016 referendum date, the EU as a single market and customs union, the 2020 Trade and Cooperation Agreement, and the economic and political effects of leaving a regional bloc.