Boris Johnson was Prime Minister of the United Kingdom from July 2019 to September 2022 and the leading political figure in the campaign to leave the European Union during his tenure. This verified explainer outlines his role in advancing Brexit, the key legislative and negotiation phases, and the policy changes that followed. It focuses on developments that remain relevant to understanding UK politics, trade, and constitutional debates. The timeline below summarizes core milestones during his term in office.
Background on the 2016 referendum and path to leadership
The United Kingdom European Union membership referendum on 23 June 2016 produced a narrow majority to leave the EU. The result prompted years of parliamentary deadlock and multiple prime ministers. Boris Johnson, a prominent Vote Leave campaigner, became Conservative leader and prime minister in July 2019, promising to deliver Brexit by 31 October 2019. His premiership thus began with the central policy objective of exiting the EU, reshaping the UK’s political and trade landscape.
The renegotiation and the revised withdrawal agreement
Upon taking office, Johnson sought to replace the Withdrawal Agreement negotiated by his predecessor, in particular the Northern Ireland Protocol. The government and EU agreed a revised deal in October 2019, which reduced some aspects of the Protocol but maintained a form of regulatory separation between Northern Ireland and Great Britain. Key elements included the creation of a UK customs zone and new procedures for movement of goods. These changes were intended to reduce friction while preserving much of the integrity of the EU single market.
Key elements of the revised Withdrawal Agreement
| Attribute | Verified Detail | Source Type |
|---|---|---|
| Revised deal announced | 17 October 2019 | UK Government and EU joint statement |
| Northern Ireland Protocol replaced | With new Protocol on Ireland/Northern Ireland | Agreed text |
| Legislation introduced | UK Parliament passed the EU (Future Relationship) Act 2020 | Public Acts |
Parliamentary passage and the EU (Future Relationship) Act 2020
The EU (Future Relationship) Act 2020, which incorporated the revised agreement and the new political declaration into UK law, passed through Parliament and received Royal Assent on 31 December 2020. This legislation enabled the UK and EU to finalize the Trade and Cooperation Agreement on 24 December 2020, avoiding a no-deal exit. The Act also established frameworks for customs, regulatory cooperation, and governance mechanisms for monitoring and dispute resolution. These domestic legal steps were essential for implementing the new relationship with the EU.
Trade and cooperation with the EU after Brexit
The Trade and Cooperation Agreement entered into force on 1 May 2021, covering trade in goods and services, data flows, and security cooperation. While removing tariffs and quotas on goods, the agreement introduced new barriers such as customs checks, rules of origin requirements, and regulatory controls. Johnson framed the arrangement as a barrier-free trade model, but businesses have faced practical challenges related to paperwork and standards alignment, especially in sectors reliant on just-in-time supply chains.
Domestic policy impact and the Union landscape
Brexit has had lasting effects on UK governance and intergovernmental relations. New policy responsibilities returned to the UK authorities, enabling reforms in areas such as fishing, agriculture, and competition policy. However, this has also led to tensions with devolved administrations in Scotland, Wales, and Northern Ireland over jurisdiction and the functioning of devolution. Debates on the Union’s stability and constitutional balance have continued, with ongoing discussions about the long-term consequences of Brexit for national cohesion and public services.
Political legacy and conclusions
Johnson’s premiership is closely associated with the delivery of Brexit and the subsequent reshaping of the UK’s external relations. His strategy prioritized a clean break with EU institutions and a bilateral trade model. While this approach achieved a ratified agreement and legislative independence, it also introduced new administrative requirements and political disputes. The long-term impact on trade performance, constitutional arrangements, and public trust remains a central theme in UK politics, making the Johnson-Brexit period a defining episode in contemporary governance.