The United Kingdom left the European Union on January 31, 2020. Under the terms of the UK-EU Withdrawal Agreement and the UK-EU Trade and Cooperation Agreement, the UK left the European single market on December 31, 2021.

The European single market consists of member states of the EU as well as – with certain exceptions – Iceland, Liechtenstein, and Norway through the European Economic Area. Switzerland is also considered a member of the European single market through bilateral treaties it has entered into with the EU, but is not a member of the European Economic Area and does not apply the entirety of EU acquis.

Opinion polling since 2020 has shown narrow support for British re-entry into the European Union. There is also public discussion of British re-entry into the European single market falling short of re-entry into the European Union, such as entry into the European Economic Area.

Age-stratified polling shows large majorities for re-entry into the EU in the 18-24 and 25-34 cohorts, with a majority in the 35-44 cohort as well.