Can the UK Rejoin the EU? Article 49 TEU, the Referendum Question and the Terms Britain Would Face
Introduction
The United Kingdom can legally seek to rejoin the European Union, but it cannot simply reverse Brexit or reactivate its former membership. For anyone asking whether the UK can rejoin the EU, the decisive provision is Article 50(5) of the Treaty on European Union (TEU). It places a state that has withdrawn and later seeks membership again under the accession procedure in Article 49 TEU (European Union, 2016, arts 49 and 50(5)).
The question has acquired renewed political significance. The UK left the EU on 31 January 2020, and the post-Brexit strategic partnership is underpinned by the Withdrawal Agreement, including the Windsor Framework, and the Trade and Cooperation Agreement (Council of the European Union, 2025). In September 2026, Prime Minister Andy Burnham said that Britain should consider longer-term options including EU membership, the single market, and a customs union (Reuters, 2026).
Political consideration of membership is not the same as commencing an Article 49 accession process. Article 49 requires the Council to act unanimously after consulting the Commission and obtaining the consent of the European Parliament. The conditions of admission and necessary Treaty adjustments would then be set out in an accession agreement requiring ratification by all contracting states according to their constitutional requirements (European Union, 2016, art. 49).
A second referendum is a separate constitutional question. EU law does not require an applicant state to hold a referendum before accession, and current UK law contains no automatic referendum requirement equivalent to the former regime under the European Union Act 2011, which was repealed through the European Union (Withdrawal) Act 2018. A future UK-wide referendum would require a legislative basis establishing the terms on which the vote would be held (European Union (Withdrawal) Act 2018; Electoral Commission, 2016).
The terms of renewed membership would be equally significant. Article 49 leaves the conditions of admission to negotiation, and Britain would not be guaranteed the opt-outs and special arrangements that accompanied its former membership (House of Commons Library, 2025). The euro, Schengen, free movement, the jurisdiction of the Court of Justice, trade policy, budget contributions, and the domestic legal effect of EU membership would all have to be assessed under the contemporary EU legal order and the terms of any eventual accession agreement.
1. Can the UK Rejoin the EU Under Article 49 TEU?
The EU Treaties expressly allow a state that has withdrawn from the Union to seek membership again. Article 50(5) of the Treaty on European Union (TEU) provides that a state which has withdrawn and later asks to rejoin is subject to the procedure in Article 49. The legal route back is thus written into the Treaty itself rather than inferred from general principles of EU law (Treaty on European Union, 2016, arts 49 and 50(5)).
This does not mean that a completed withdrawal can simply be reversed. Under Article 50(3), the Treaties ceased to apply to the United Kingdom when its withdrawal took effect on 31 January 2020. The Withdrawal Agreement then provided a transition period until 31 December 2020, during which Union law continued to apply to and in the UK even though the country was no longer a Member State (Council of the European Union, 2020).
The distinction is fundamental. Before withdrawal became effective, the legal question concerned whether the United Kingdom could remain a Member State by revoking its Article 50 notification. After withdrawal, the relevant question became whether it could obtain membership again through accession. Article 50(5) directs that second question to Article 49.
1.1 Article 50(5) and the Legal Route Back
Article 50(5) does not create a special procedure for returning states. Nor does it provide for reinstatement by agreement outside the ordinary accession framework. Its function is to make Article 49 applicable when a state that has already withdrawn later seeks membership again (Treaty on European Union, 2016, art. 50(5)).
That position differs from the judgment in Wightman and Others v Secretary of State for Exiting the European Union, Case C-621/18. The Court of Justice held that a Member State could revoke its Article 50 notification unilaterally while the withdrawal process remained open, subject to the conditions identified by the Court. The effect would be to confirm continued membership on unchanged terms rather than to leave the Union and apply again (CJEU, 2018, paras 74–75).
Wightman concerned preservation of an existing membership before withdrawal became effective. It did not establish a mechanism for restoring membership after withdrawal had occurred. Once the UK ceased to be a Member State on 31 January 2020, unilateral revocation was no longer an alternative to accession.
Article 49 consequently supplies the relevant legal framework for any future British return. It requires an application for membership followed by decisions within the Union, negotiation of the conditions of admission, and conclusion and ratification of an accession agreement. Re-entry would be a new act of accession, not a continuation of the Article 50 process.
1.2 Rejoining Is a New Accession
A returning United Kingdom would enter Article 49 as an applicant state. Its previous membership would not give it a treaty-based right to revive the legal arrangements that applied before Brexit. Article 49 instead provides for the conditions of admission and any necessary Treaty adjustments to be agreed through the accession process (Treaty on European Union, 2016, art. 49).
This point is particularly important for Britain’s former opt-outs and special arrangements. The House of Commons Library has noted that a new UK application would not be guaranteed the former exemptions relating to areas such as the euro and Schengen, or the previous budget rebate (House of Commons Library, 2025). Those arrangements could not simply be treated as continuing rights inherited from the UK’s earlier membership.
Past membership would still form part of the practical context in which a future application was assessed. Britain previously implemented extensive parts of the EU acquis and participated in Union institutions for decades. Contemporary accession practice, however, assesses an applicant’s present alignment and capacity to implement the acquis then in force; historical compliance does not by itself establish current readiness across all fields of EU law (European Commission, 2026).
2. Is the UK Trying to Rejoin the EU?
Current EU enlargement materials do not place the United Kingdom among the Union’s candidate countries. The Council presently lists nine candidates and describes membership application, candidate status, accession negotiations, and membership as distinct stages of the enlargement process. The UK does not appear in that current enlargement record (Council of the European Union, 2026).
The political position is more fluid. Andy Burnham became Prime Minister on 20 July 2026, and in September he said that Britain should consider several possible long-term relationships with the EU, including membership, participation in the single market, and a customs union. He did not announce an Article 49 application or present rejoining as an immediate government decision (UK Government, 2026; Reuters, 2026).
Burnham’s personal position is more specific than current government policy. He has said that he would like to see Britain rejoin the EU within his lifetime, while also making clear that this does not mean pursuing re-entry immediately. His stated approach is to compare several possible relationships with the Union before deciding which course should be followed (The Guardian, 2026).
These distinctions are legally important. Joining a customs union, participating more closely in the single market, or expanding regulatory and security cooperation would not by themselves make Britain an EU applicant. Membership engages Article 49; other forms of closer integration may be pursued through different legal arrangements between the UK and the Union.
A formal application addressed to the Council would provide the clearest legal indication that political debate had moved into an accession process. Article 49 also requires notification of the European Parliament and national parliaments and then engages the institutional decisions associated with accession. Until those steps occur, discussion of rejoining remains different from an Article 49 membership proceeding.
3. How Article 49 Accession Would Work
Article 49 establishes the Treaty framework for admission to the European Union, but it does not codify every stage used in contemporary enlargement practice. It identifies who may apply, the principal institutional approvals required, and the legal form through which accession conditions become binding. Administrative procedures such as screening and negotiating clusters arise from enlargement practice rather than from the wording of Article 49 itself.
An application does not automatically produce candidate status or open negotiations. Current Council materials distinguish the application, candidate-status, negotiation, and membership stages, while the pace of accession depends on the applicant’s fulfillment of the applicable conditions (Council of the European Union, 2026).
Modern accession practice also examines the applicant’s ability to adopt and implement the acquis. Screening, benchmarks, negotiating chapters, and clusters are used to assess preparedness and organize negotiations. Their present form reflects the Union’s contemporary enlargement methodology and should not be confused with permanent procedural requirements written into Article 49 (European Commission, 2026).
3.1 Eligibility, Values, and the Copenhagen Criteria
Article 49 permits any European state to apply if it respects the values identified in Article 2 TEU and is committed to promoting them. Those values include human dignity, freedom, democracy, equality, the rule of law, and respect for human rights, including the rights of persons belonging to minorities (Treaty on European Union, 2016, arts 2 and 49).
Treaty eligibility operates alongside the Copenhagen criteria developed through the European Council’s enlargement policy. These require stable institutions guaranteeing democracy, the rule of law, human rights and protection of minorities; a functioning market economy capable of coping with competitive pressures; and the capacity to take on and effectively implement the obligations of membership (European Commission, n.d.).
For a former Member State, past participation does not displace these requirements. Accession policy assesses whether a candidate can comply with the EU rules and obligations applicable at the time of the new application. The acquis may have changed considerably since a state’s previous membership ended.
Eligibility to apply is also different from entitlement to join. Article 49 identifies states that may seek membership, but admission remains dependent on institutional consent, negotiated accession terms, and ratification. Satisfying the threshold for an application does not create a unilateral right to membership.
3.2 Unanimity, Consent, and the Accession Treaty
A British application would be addressed to the Council. Article 49 requires the European Parliament and national parliaments to be notified, and the Council must act unanimously after consulting the Commission and obtaining the European Parliament’s consent. Parliament gives that consent by a majority of its component members (Treaty on European Union, 2016, art. 49).
The unanimity requirement gives every existing Member State a formal role in admission. Support from the Commission or from individual governments could not substitute for the Council decision required by the Treaty. Accession is consequently both an institutional process and an agreement among states.
If negotiations were opened, contemporary enlargement practice would examine the applicant’s alignment with the acquis in detail. Commission screening helps determine preparedness, and benchmarks may be used before negotiating areas are opened or provisionally closed. Current methodology organizes much of this work through policy chapters grouped into thematic clusters (European Commission, 2026).
Successful completion of negotiations would still not itself confer membership. Article 49 requires the conditions of admission and the necessary adjustments to the Treaties to be embodied in an agreement between the Member States and the applicant. That accession agreement must then be ratified by all contracting states according to their respective constitutional requirements.
Nothing in Article 49 creates a separate fast-track procedure for former Member States. Britain’s previous experience of EU law would form part of the factual circumstances considered in assessing present alignment, but it would not remove the Treaty requirements governing accession.
4. Would Britain Need Another Referendum?
EU law does not require the United Kingdom to hold a referendum before applying for or acceding to the Union. Article 49 instead requires the accession agreement to be ratified by all contracting states according to their respective constitutional requirements. The method used on the British side is consequently a question of UK constitutional law as well as political choice.
The United Kingdom previously had statutory referendum requirements for specified EU decisions under the European Union Act 2011. Those provisions no longer operate: the Act was repealed through the European Union (Withdrawal) Act 2018 and the associated commencement legislation (European Union (Withdrawal) Act 2018, Sch. 9).
There is no standing statutory referendum mechanism that would automatically activate because a government sought EU membership. A new UK-wide referendum would require legislation establishing the vote and its legal framework. The Electoral Commission confirms that Parliament must legislate for a UK referendum and has statutory responsibilities concerning the intelligibility of proposed questions (Electoral Commission, n.d.).
4.1 Miller, Referendums, and Parliamentary Authority
The Supreme Court’s decision in R (Miller) v Secretary of State for Exiting the European Union [2017] UKSC 5 did not create a general constitutional requirement for referendums on EU membership. The principal issue was whether ministers could give the Article 50 withdrawal notification through prerogative power without prior statutory authorization.
By a majority of eight to three, the Court held that legislation was required. Withdrawal would alter domestic law and remove rights that had effect through the European Communities Act 1972, changes that ministers could not accomplish through the foreign-affairs prerogative alone (Miller, 2017).
The Court separately considered the legal significance of the 2016 referendum. It held that the effect of a referendum depends on the statute authorizing it. The European Union Referendum Act 2015 provided for the vote but did not specify the legal consequences of either outcome, so the referendum did not itself change domestic law (Miller, 2017, paras 118–124).
Miller is relevant to future debates because it distinguishes political authorization from legal change. It did not decide the constitutional procedure for a future accession under Article 49, nor did it hold that another referendum would be legally necessary. Its more limited significance lies in confirming that changes to domestic law requiring statutory authority must be made through Parliament.
4.2 When a Referendum Could Take Place
If Parliament chose to provide for another referendum, its timing would determine what voters were being asked to decide. A vote held before an Article 49 application or before negotiations had produced agreed accession terms could authorize the pursuit of membership, but it could not submit a final accession package that did not yet exist.
A referendum held after negotiations could instead be framed around agreed membership terms. Article 49 neither requires that sequence nor prevents the United Kingdom from choosing it. The constitutional design would depend on the legislation enacted for the referendum and on the domestic steps required to implement accession.
Fresh legislation would also have to establish the referendum’s operative framework, including the question and the rules governing the vote. The Electoral Commission is required by law to assess the intelligibility of proposed UK referendum questions. The question used for the 2016 referendum does not continue as a standing legal formula for any future vote on EU accession; a new referendum would require a new statutory basis (Electoral Commission, n.d.; European Union Referendum Act 2015).
5. What Terms Would Britain Face?
Article 49 does not provide for restoration of a former member’s previous terms. It requires the conditions of admission and any adjustments to the EU Treaties necessitated by accession to be contained in an agreement between the Member States and the applicant state. A returning United Kingdom would accordingly negotiate the terms of a new accession rather than reactivate the legal package that applied before Brexit (Treaty on European Union, 2016, art. 49).
This distinction is significant because Britain previously held several exceptional arrangements. Its former position included treaty-based provisions concerning the euro and Schengen, as well as a distinctive budget correction. A new application would not carry a legal entitlement to recover those arrangements merely because the UK had enjoyed them during its earlier membership (House of Commons Library, 2025).
That does not mean that every special arrangement would be legally impossible. Article 49 permits admission conditions and Treaty adjustments to be negotiated through the accession agreement. A permanent exception could, in principle, form part of such an agreement if the necessary parties accepted it and the agreement obtained the required ratifications. Britain could not, however, claim its former exceptions as pre-existing rights.
Transitional arrangements present a different issue. Accession treaties may contain provisions dealing with implementation periods, safeguards, institutional adjustments, financial arrangements, and temporary derogations. Such measures facilitate accession to the existing EU legal order; they are not equivalent to a permanent exemption from a central membership obligation.
6. Euro, Schengen, and Free Movement
The euro, Schengen, and free movement are often grouped together in political debate, but they rest on different legal foundations. Rejoining the EU would not necessarily mean that every aspect of these regimes became operational for the UK on the same day. The legal position in each area depends on the ordinary rules of membership and any modifications lawfully agreed through accession.
Britain’s previous membership cannot supply the answer by itself. Its earlier arrangements depended on specific treaty provisions and negotiated exceptions that formed part of the legal settlement applicable before withdrawal. Article 49 does not automatically revive them.
Transitional implementation must also be distinguished from permanent exclusion. EU accession practice has permitted temporary measures in particular fields while preserving the principle that the new Member State joins the Union’s legal order and assumes the obligations of membership.
6.1 The Euro and Britain’s Former Opt-Out
The United Kingdom previously possessed a specific treaty-based exemption concerning the euro. Protocol No. 15 provided that the UK was not obliged to adopt the single currency unless its government and Parliament decided otherwise. That position was exceptional rather than the general rule for Member States outside the euro area (Protocol No. 15, 2016).
Under the contemporary framework, Denmark retains a Treaty opt-out from participation in the euro. Other EU Member States outside the euro area are expected to adopt the currency once they satisfy the applicable convergence conditions, although EU law does not prescribe a fixed date by which those conditions must be met (European Commission, n.d.).
A returning Britain should consequently not be described as having to adopt the euro immediately upon accession. Absent a newly negotiated exemption, the ordinary framework applicable to Member States that have not yet adopted the currency would govern the UK. Recreating a British opt-out would require agreement through the accession process rather than reliance on the former Protocol.
6.2 Schengen and the Common Travel Area
EU accession and the removal of internal border controls under Schengen are not necessarily simultaneous. Protocol No. 19 provides that the Schengen acquis and measures building upon it must be accepted in full by states seeking EU membership. In enlargement practice, however, some Schengen provisions—particularly the abolition of controls at internal borders—have taken effect only after subsequent evaluation and Council approval (Protocol No. 19, 2016; Council of the European Union, 2023).
Britain’s former position was exceptional. While an EU Member State, the UK did not participate in the general abolition of internal border controls and instead participated selectively in parts of the Schengen acquis. Its position rested on specific Treaty arrangements rather than on a general right of Member States to choose which Schengen rules applied to them (Protocol No. 19, 2016).
The Common Travel Area with Ireland raises a related but distinct issue. It predates both states’ membership of the European Communities and has continued after Brexit. During UK membership, Protocol No. 20 expressly accommodated the ability of the United Kingdom and Ireland to maintain arrangements concerning movement within the Common Travel Area (Protocol No. 20, 2016).
Rejoining the EU would not, by itself, establish that the Common Travel Area had to disappear. Nor could Britain assume that its former Schengen and border arrangements would automatically return. The relationship between Schengen obligations, border controls, and the Common Travel Area would have to be addressed through the terms of a new accession.
6.3 Free Movement and Transitional Rules
Free movement would present a different legal question. Article 45 TFEU protects the free movement of workers and prohibits nationality-based discrimination in employment, subject to the exceptions recognized by EU law. EU citizenship also carries Treaty rights concerning movement and residence within the territory of the Member States (Treaty on the Functioning of the European Union, 2016, arts 20, 21 and 45).
Accession treaties have sometimes allowed temporary restrictions on access to national labor markets for workers from newly admitted states. Such arrangements should not be described as a general suspension of free movement. The transitional regime applied following Croatia’s accession, for example, concerned particular aspects of worker access while other movement and residence rights continued to operate under EU law (European Commission, 2015).
A returning United Kingdom would consequently have no ordinary unilateral power to remain a full Member State while disapplying EU free-movement law through domestic immigration policy. Any permanent exemption would require a specific legal basis agreed through accession. Temporary labor-market measures, if negotiated, would be legally different from a general opt-out from free movement.
7. Courts, Trade, Budget, and Domestic Effect
Rejoining would extend beyond questions of borders, migration, or the single currency. Full membership would return the United Kingdom to the institutional and legal system through which EU law is interpreted, enforced, financed, and applied across the Member States.
That position differs fundamentally from preferential access to the European market. The Trade and Cooperation Agreement regulates a relationship between the EU and a non-member United Kingdom; accession would instead place Britain within the Union’s legal order.
Existing UK arrangements concerning trade, domestic law, regulatory authority, and public finances would consequently have to be reconciled with the obligations arising from membership and with the terms negotiated in the accession agreement.
7.1 CJEU, Trade Policy, and the EU Budget
Renewed membership would restore the ordinary judicial mechanisms of EU law in relation to the United Kingdom. Under Article 19 TEU and the jurisdictional provisions of the TFEU, the Court of Justice ensures observance of EU law, national courts may refer questions of EU law for preliminary rulings, and the Commission may bring infringement proceedings against Member States that fail to fulfil their obligations (Treaty on European Union, 2016, art. 19; Treaty on the Functioning of the European Union, 2016, arts 258–260 and 267).
The implications would also extend to trade policy. The customs union and common commercial policy are areas of exclusive EU competence, while Article 207 TFEU establishes the framework for the Union’s common commercial policy. A Member State cannot maintain an autonomous national trade policy in areas where the Treaties confer exclusive competence on the Union (Treaty on the Functioning of the European Union, 2016, arts 3 and 207).
Britain’s existing trade agreements would consequently require examination for compatibility with renewed EU membership. Accession precedent has required incoming states to withdraw from specified third-country free trade agreements and eliminate incompatibilities between existing international commitments and EU obligations (Act of Accession, 2003, art. 6(10)). This does not mean that every UK agreement would automatically terminate, but incompatible commitments would have to be amended, replaced, or otherwise brought into conformity with EU law.
Budget contributions would form another part of the membership settlement. The historical UK rebate was a distinctive feature of Britain’s former financial relationship with the Union, but a returning UK would have no automatic right to restore it. The House of Commons Library has identified the rebate among the former arrangements that would not be guaranteed in a new accession process (House of Commons Library, 2025).
Financial provisions could nevertheless form part of the accession negotiations. The EU budget continues to contain correction mechanisms for certain Member States, although these are not equivalent to the former UK rebate (European Commission, n.d.). Any future British financial arrangement would require its own legal basis rather than operating as a continuation of the pre-Brexit settlement.
7.2 CRAG Scrutiny and Implementing Legislation
On the UK side, conclusion of an accession treaty would not by itself reproduce the domestic legal effects of EU membership. Under current law, treaties falling within Part 2 of the Constitutional Reform and Governance Act 2010 are generally subject to parliamentary scrutiny before ratification. Section 20 establishes the ordinary 21-sitting-day scrutiny period and provides mechanisms through which Parliament may object to ratification (Constitutional Reform and Governance Act 2010, s. 20).
CRAG does not establish a general requirement for Parliament to approve every treaty through an affirmative vote. The precise procedure applicable to a future accession treaty cannot, however, be fixed in advance. Parliament could adopt specific legislation modifying the ordinary statutory framework, so the relevant procedure would ultimately depend on the law in force when accession was pursued.
Treaty ratification must also be distinguished from domestic implementation. In R (Miller) v Secretary of State for Exiting the European Union [2017] UKSC 5, the Supreme Court confirmed the constitutional limits of the treaty prerogative where changes to domestic law require parliamentary authority. Renewed EU membership would require primary legislation capable of giving the accession settlement and EU law the necessary domestic legal effects (Miller, 2017).
A referendum would not remove that requirement. Even if Parliament established a referendum and voters approved rejoining, the vote would not itself recreate the statutory framework required for EU membership. Parliament would still have to legislate for the domestic consequences of accession.
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Conclusion
The United Kingdom can legally seek to rejoin the European Union, but the route is accession rather than reversal of Brexit. Article 50(5) TEU directs a state that has withdrawn and later asks to rejoin to the Article 49 procedure. Membership would depend on the institutional decisions, negotiations, accession agreement, and ratifications required by that process.
Current UK law does not automatically require another referendum, although Parliament could legislate for one. A referendum could provide political authorization for pursuing membership or approval of negotiated terms, but it would not eliminate the need for domestic legislation implementing accession.
The terms of any return would be as significant as the legal possibility itself. Britain would not automatically recover its former euro opt-out, Schengen arrangements, budget rebate, or other special provisions. Their treatment, alongside free movement, CJEU jurisdiction, trade policy, financial obligations, and domestic implementation, would depend on the EU legal framework and the accession terms ultimately accepted by the United Kingdom and the existing Member States.
References
Act concerning the conditions of accession of the Czech Republic, Estonia, Cyprus, Latvia, Lithuania, Hungary, Malta, Poland, Slovenia and Slovakia and the adjustments to the Treaties on which the European Union is founded (2003) art. 6, OJ L 236, 23 September 2003, pp. 34–35. Available at: https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A12003T006 (Accessed: 20 September 2026).
Cabinet Office and Home Office (2026) ‘Common Travel Area: rights of UK and Irish citizens’ [online]. Last updated 1 January 2026. Available at: https://www.gov.uk/government/publications/common-travel-area-guidance (Accessed: 20 September 2026).
Constitutional Reform and Governance Act 2010 (2010) 8 April 2010, 2010 c. 25. Available at: https://www.legislation.gov.uk/ukpga/2010/25/contents (Accessed: 20 September 2026).
Council of the European Union (2020) ‘Brexit: Council adopts decision to conclude the withdrawal agreement’, 30 January 2020 [online]. Available at: https://www.consilium.europa.eu/en/press/press-releases/2020/01/30/brexit-council-adopts-decision-to-conclude-the-withdrawal-agreement/ (Accessed: 20 September 2026).
Council of the European Union (2023) ‘Schengen area: Council agrees to lift air and maritime internal border controls with Bulgaria and Romania’, 30 December 2023 [online]. Available at: https://www.consilium.europa.eu/en/press/press-releases/2023/12/30/schengen-area-council-takes-move-towards-lifting-border-controls-with-bulgaria-and-romania/ (Accessed: 20 September 2026).
Council of the European Union (2025) ‘EU-UK withdrawal agreement’ [online]. Last reviewed 28 May 2025. Available at: https://www.consilium.europa.eu/en/policies/the-eu-uk-withdrawal-agreement/ (Accessed: 20 September 2026).
Council of the European Union (2026) ‘EU enlargement’ [online]. Last reviewed 9 July 2026. Available at: https://www.consilium.europa.eu/en/topics/eu-enlargement/ (Accessed: 22 September 2026).
Court of Justice of the European Union (2018) Wightman and Others v Secretary of State for Exiting the European Union, Case C-621/18, judgment of 10 December 2018, ECLI:EU:C:2018:999. Available at: https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:62018CJ0621 (Accessed: 22 September 2026).
Electoral Commission (2016) ‘Report: 23 June 2016 referendum on the UK’s membership of the European Union’ [online]. Available at: https://www.electoralcommission.org.uk/research-reports-and-data/our-reports-and-data-past-elections-and-referendums/report-23-june-2016-referendum-uks-membership-european-union (Accessed: 22 September 2026).
Electoral Commission (n.d.-a) ‘Referendum question research’ [online]. Available at: https://www.electoralcommission.org.uk/research-reports-and-data/referendum-question-research (Accessed: 22 September 2026).
Electoral Commission (n.d.-b) ‘What we do in referendums’ [online]. Available at: https://www.electoralcommission.org.uk/about-us/our-role-and-responsibilities/what-we-do-referendums (Accessed: 22 September 2026).
European Commission (2015) Report from the Commission to the Council on the Functioning of the Transitional Arrangements on Free Movement of Workers from Croatia (First phase: 1 July 2013–30 June 2015), COM(2015) 233 final, 29 May 2015. Available at: https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=COM:2015:0233:FIN (Accessed: 22 September 2026).
European Commission (2026) ‘Factsheet: State of play – EU accession negotiations’ [online]. Published 24 October 2025, last updated 22 July 2026. Available at: https://enlargement.ec.europa.eu/factsheet-state-play-eu-accession-negotiations_en (Accessed: 22 September 2026).
European Commission (n.d.-a) ‘Conditions for membership’ [online]. Available at: https://enlargement.ec.europa.eu/enlargement-policy/conditions-membership_en (Accessed: 22 September 2026).
European Commission (n.d.-b) ‘Rebates: correction mechanisms’ [online]. Available at: https://commission.europa.eu/strategy-and-policy/eu-budget/long-term-eu-budget/2021-2027/revenue/rebates_en (Accessed: 22 September 2026).
European Commission (n.d.-c) ‘Who can join and when?’ [online]. Available at: https://economy-finance.ec.europa.eu/euro/enlargement-euro-area/who-can-join-and-when_en (Accessed: 23 September 2026).
European Union Act 2011 (2011) 19 July 2011, 2011 c. 12. Available at: https://www.legislation.gov.uk/ukpga/2011/12/contents (Accessed: 25 September 2026).
European Union Referendum Act 2015 (2015) 17 December 2015, 2015 c. 36. Available at: https://www.legislation.gov.uk/ukpga/2015/36/contents (Accessed: 25 September 2026).
European Union (Withdrawal) Act 2018 (2018) 26 June 2018, 2018 c. 16. Available at: https://www.legislation.gov.uk/ukpga/2018/16/contents (Accessed: 25 September 2026).
House of Commons Library (2025) Debate on the UK applying to join the European Union, Research Briefing CDP-2025-0067, 18 March 2025. Available at: https://commonslibrary.parliament.uk/research-briefings/cdp-2025-0067/ (Accessed: 30 September 2026).
Prime Minister’s Office, 10 Downing Street and Burnham, A. (2026) ‘Andy Burnham’s first speech as Prime Minister: 20 July 2026’ [online]. Available at: https://www.gov.uk/government/speeches/andy-burnhams-first-speech-as-prime-minister-20-july-2026 (Accessed: 30 September 2026).
Protocol (No. 15) on certain provisions relating to the United Kingdom of Great Britain and Northern Ireland (2016) OJ C 202, 7 June 2016, pp. 284–286. Available at: https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:12016E/PRO/15 (Accessed: 30 September 2026).
Protocol (No. 19) on the Schengen acquis integrated into the framework of the European Union (2016) OJ C 202, 7 June 2016, pp. 290–292. Available at: https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:12016E/PRO/19 (Accessed: 30 September 2026).
Protocol (No. 20) on the application of certain aspects of Article 26 of the Treaty on the Functioning of the European Union to the United Kingdom and to Ireland (2016) OJ C 202, 7 June 2016, pp. 293–294. Available at: https://eur-lex.europa.eu/legal-content/EN/ALL/?uri=CELEX:12016M/PRO/20 (Accessed: 30 September 2026).
Reuters (2026) ‘Burnham says UK should weigh post-Brexit EU options, including rejoining’, 30 September 2026 [online]. Available at: https://www.reuters.com/world/uk/burnham-says-britain-should-weigh-eu-options-including-rejoining-bloc-2026-09-30/ (Accessed: 30 September 2026).
Supreme Court of the United Kingdom (2017) R (on the application of Miller and another) v Secretary of State for Exiting the European Union [2017] UKSC 5, judgment of 24 January 2017. Available at: https://www.supremecourt.uk/cases/uksc-2016-0196 (Accessed: 30 September 2026).
The Guardian (2026) ‘No 10 gathering evidence on public support for UK rejoining EU’, 30 September 2026 [online]. Available at: https://www.theguardian.com/politics/2026/sep/30/no-10-gathering-evidence-public-support-rejoining-eu-reversing-brexit (Accessed: 30 September 2026).
Treaty on European Union (2016) consolidated version, OJ C 202, 7 June 2016, pp. 13–45. Available at: https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=OJ:C:2016:202:TOC (Accessed: 30 September 2026).
Treaty on the Functioning of the European Union (2016) consolidated version, OJ C 202, 7 June 2016, pp. 47–200. Available at: https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=OJ:C:2016:202:TOC (Accessed: 30 September 2026).