This article is updated regularly as events unfold.
The United Kingdom left the European Union — now an economic and political partnership of 27 countries — on January 31, 2020 under the terms of a negotiated divorce deal, bringing to an end 47 years of British membership of the EU and the institutions that preceded it.
"Brexit" — the term used to describe Britain's EU departure — represents the most important constitutional shake-up the UK has known since it joined the six-nation European Economic Community in 1973. It is also the first time the European institution has lost a member.
A "transition period" keeping most pre-departure arrangements in place ended on December 31, 2020, finally bringing the transformation that has beckoned since the June 2016 referendum when the UK voted to leave the EU.
Released from EU trading and "free movement" rules, the UK is introducing its own policies on trade and immigration — as the EU can now do regarding British nationals. Other changes affect people, travel and business.
A last-minute deal on post-Brexit trade and future EU-UK relations was struck on Christmas Eve 2020 after months of deadlocked negotiations. It allows for tariff-free, quota-free access to each other's markets for goods — but not services — and also covers future competition, fishing rights, and cooperation on matters such as security.
However, the agreement has not prevented significant disruption to trade, particularly to UK exports to the EU, due to new border rules — and red tape — with the UK now outside the EU's Single Market and Customs Union.
The immediate post-Brexit period has seen the UK and EU clash over arrangements for Northern Ireland and vaccine exports in the midst of the coronavirus pandemic. Anger among unionist communities over new trading rules brought a spate of rioting in early April.
Although part of the UK, Northern Ireland continues to follow some EU rules under the divorce deal to keep an open land border with the Irish Republic, an EU member. As new border formalities disrupted supplies from Great Britain, the UK government moved unilaterally to extend a grace period on some food checks. The EU accused the UK of violating the deal and launched legal action.
Latest developments (to April 12, 2021):
'Taking back control': The background to Brexit
The UK voted to leave the EU by 52% to 48% in a referendum in June 2016. The campaign message that the country wanted to "take back control" of its borders, money and laws resonated with voters.
The vote followed decades of increasing hostility to the European project, which enforced the supremacy of EU law in certain areas and whose "freedom of movement" principle led to millions of EU citizens moving to the UK to work and settle.
Other factors cited as having had an influence were a rise in nationalist sentiment, particularly in England, as well as austerity and frustration with traditional politics. The outcome has fed into a wider debate over the role of the nation-state and the rise of populism in an age of globalisation.
The vote revealed strains between the UK's individual countries: England (53%) and Wales (52.5%) voted to leave the EU, whereas Scotland and Northern Ireland voted by 62% and 56% respectively to remain. Other divisions have also been exposed: between metropolitan areas and small towns for example, and different age groups and social classes.
The referendum's aftermath plunged the UK into its worst political and constitutional crisis since the Second World War. Brexit day was repeatedly delayed amid deadlock in the British parliament over the divorce terms.
There has been concern that the prolonged, acrimonious process — compounded by the pandemic and its economic fallout — has shifted attention from major global challenges, not least the climate emergency. For many in Europe, the UK-EU split weakens the continent at a time when other countries, notably China and Russia, have been increasingly assertive.
WHERE WE ARE NOW: EU and UK finally split for real
January 1, 2021 — more than four-and-a-half years after the UK's EU referendum — was the day that the full effects of the country's departure from the European Union finally began to be felt.
The UK ceased to be a member of the EU from February 1, 2020, and left the bloc's institutions.
However, it continued to follow EU rules during a post-Brexit transition period that kept most arrangements from the UK's EU membership in place until its expiry at the end of 2020.
Significant changes have now begun kicking in — most of these irrespective of the last-minute deal on trade and future ties. The most immediately visible impact has been on UK exports to the EU.
New border rules
As of January 1, 2021, the UK is no longer part of the EU's Single Market and Customs Union, and is free to implement trade deals struck with third countries.
This brings new customs formalities and regulatory controls between the EU and the UK. The EU had stressed that these would bring more red tape and "longer delivery times", a warning that appears to have been borne out with many reports of disruption. This follows many cries of alarm from British business in 2020 over the state of UK preparations.
The UK decided to phase in new border checks on imports and has since announced a further six-month delay on their imposition. However, some British exports to the EU have been severely disrupted due to new bureaucracy or have even ground to a halt because of curtailed market access.
The supply of goods from Britain to Northern Ireland has also been affected under new arrangements set out in the Brexit divorce deal (see below).
Free movement and immigration
Other rules that cease to apply from January 2021 include those on freedom of movement (a conditional not absolute right of EU citizens to move to other EU countries to live and work), cross-border travel and personal rights.
EU citizens no longer have the right to move to the UK to work and settle, and vice versa, and travel between Britain and the continent now involves new restrictions. The UK is introducing a new immigration policy from January 2021. EU nationals no longer have preferential treatment; instead, the government plans a new points-based system to attract skilled workers.
EU citizens already resident in the UK by the end of 2020 — and Britons living on the continent — can remain with guaranteed rights under the terms of the Brexit divorce deal (see Divorce Deal section below). However, there have been many complaints about how this is working out in practice for EU nationals in the UK.
The UK is also leaving the EU's Erasmus+ student exchange programme.
Row over Northern Ireland Protocol
New arrangements for Northern Ireland have been the source of early post-Brexit tension, exacerbated by a row between the UK and the EU over coronavirus vaccines. Anger among unionist communities over new trading arrangements contributed to a spate of rioting in early April.
There have been calls for the Northern Ireland Protocol — part of the EU-UK divorce deal setting out a framework for post-Brexit operations — to be renegotiated.
The Protocol tries to reconcile the UK's freedom to diverge from EU rules and standards, with the political imperative of keeping the land border with the Irish Republic open. It effectively creates a regulatory border between Britain and Northern Ireland, which remains aligned to EU Single Market rules and follows the EU customs code.
New red tape demands on certain goods entering Northern Ireland from the British mainland have led to disruption and some shortages since January 1.
The UK government has decided to extend until 1 October a three-month grace period on agri-food controls between Britain and Northern Ireland to allow businesses to adapt to new arrangements. The European Commission called the move "a violation" of the trade deal and vowed to take legal action.
Tensions became exacerbated in late January when the European Commission moved to control vaccine exports amid a crisis over supplies. To include transport over the border from the Republic of Ireland to Northern Ireland, the Commission briefly proposed invoking emergency provisions under Article 16 of the Protocol, which allows either side to override parts of the deal.
The plan, a major political blunder, was quickly ditched and the EU recognised its error. But despite a torrent of criticism it has rejected calls from the UK for the rules covering post-Brexit trade to be changed.
It's a Deal! Post-Brexit accord struck at 11th hour
London and Brussels had been racing against time throughout 2020 to reach an agreement on the future EU-UK relationship, to take effect from January 2021. Failure would have seen the two sides revert to basic international trading rules, increasing costs and disruption, and leaving arrangements on other matters in limbo (see "No Deal" sections below).
The main obstacles to a deal were EU fishing rights in UK waters, safeguards to ensure fair competition, and a mechanism to enforce a deal.
This all came amid the COVID-19 pandemic and the greatest economic crisis in Europe since World War II, which calls for international cooperation and action to ease catastrophic problems, not exacerbate them.
Although the deal struck on Christmas Eve 2020 came too late to allow a conventional ratification process to take place, it has since been approved by EU national leaders and the UK parliament. It will be applied provisionally, awaiting ratification by the European Parliament in the New Year.
What's in the EU-UK agreement on trade and future ties?
The post-Brexit EU-UK deal on trade and future relations preserves tariff-free, quota-free access to each other's markets for goods.
It banished the threat of a catastrophic "no-deal scenario" that could have sent thousands of businesses to the wall.
However, it comes with many strings attached.
Trade and competition
The two sides can diverge on the likes of employment and environmental standards, but there are safeguards — a "rebalancing mechanism" governed by arbitration — to ensure fair competition.
The UK is beyond the remit of EU law or the European Court of Justice (ECJ). But challenges are possible in each other's courts, and punitive measures may be taken if subsidies distort trade.
And for service industries — highly important to the UK — further uncertainty beckons, as the deal contains only vague commitments. Financial services are not covered at all, to be dealt with by a separate process.
The trade deal brought a five-and-a-half-year transition period on fisheries — one of the main stumbling blocks in the negotiations. During that time, EU access to UK waters will be cut by a quarter, and British quotas will be increased.
Annual negotiations will then take place, but the EU can take retaliatory action if access is further reduced. And the UK, which sells most of its fish into the EU, is likely to continue to need the European market.
There will still be cross-border police investigations and law enforcement. The UK will remain in some EU security exchange programmes, but will no longer be part of the European Arrest Warrant or Europol.
The UK will also stay in the European Convention on Human Rights.
Scientific cooperation will continue with the UK still a paying member of the EU's Horizon Europe programme for seven years. It will also remain in Copernicus and Euratom, but leaves the EU's Erasmus+ student exchange programme.
Several other key policy areas are excluded from the accord.
"Foreign policy, external security and defence cooperation is not covered by the Agreement as the UK did not want to negotiate this matter," the European Commission said in its statement.
"As of 1 January 2021, there will therefore be no framework in place between the UK and the EU to develop and coordinate joint responses to foreign policy challenges, for instance, the imposition of sanctions on third-country nationals or economies," it added.
Supervision and dispute settlement
A joint Partnership Council is set up under the deal to supervise its application. It has representatives from both sides, will meet at least once a year, and has the power to change parts of the deal if errors come to light.
A separate arbitration and dispute settlement mechanism is set up, which does not rely on EU law and includes no role for the European Court of Justice.
UK trade deals with non-EU countries
From 2021, the UK will pursue an independent trade policy and can implement its own trade deals with other countries.
The British government has been working to "roll over" dozens of EU trade deals with third countries which no longer apply to the UK.
Running parallel to the Brexit saga has been the UK's evolving relationship with the United States, the most important of Britain's non-EU partners with which it hopes to strike a future trade deal. President-Elect Joe Biden has warned this will be impossible if the Irish peace accord is undermined.
Some trade experts say the UK faces a key choice over regulatory alignment: whether to stay close to EU rules to access the European market, or follow American regulation.
The struggle to negotiate the future UK-EU relationship
Following the UK's departure from the bloc in January 2020, the EU's chief negotiator Michel Barnier and his team were granted a new mandate from the European Council — made up of national leaders from the EU27 countries — to negotiate the post-Brexit EU-UK relationship. The UK under Boris Johnson's new government also set out its position.
The negotiations which began in March 2020 covered trade in goods, plus a wide range of other areas including services, fishing and farming, aviation, security cooperation, data policy, education and science.
An agreement needed to be ready to come into effect when the transition period expired at the end of December. In practice a series of missed deadlines as the process dragged on meant there was no longer enough time for a conventional ratification process and for both sides to get ready for January 1.
Months of negotiations brought slow progress and no breakthrough on key issues: competition, fisheries and governance (a mechanism for dispute settlement and enforcement). Both sides’ red lines meant they were staring at a potential economic no-deal "cliff-edge" as 2020 neared its end.
What would a 'no-deal' scenario have meant in practice?
The "no deal" talked about throughout 2020 referred not to the terms of the UK's exit from the EU — but to the potential failure to reach agreement on trade and future ties by the end of the 11-month transition period.
Without an agreement on the future relationship, barriers to trade and other aspects of life between the EU and the UK would have been aggravated.
Boris Johnson said "a trading arrangement with the EU like Australia’s... would be a good outcome for the UK". Australia however has no trade deal with the EU. After the trade talks breakthrough on December 24, Johnson lauded a 'Canada-style' agreement with the EU — although the reality is somewhat different.
With no deal, the EU and the UK would have had to trade on World Trade Organization (WTO) terms, bringing tariffs and non-tariff barriers. Here, each member must grant the same market access to all other members – except developing countries and those that have free trade agreements.
The friction that will result anyway as a result of the UK's exit from the EU's trading structures would have been aggravated by the absence of a trade deal. This would have hit the UK's economy but also those of its closest continental neighbours — and Ireland.
Other important matters such as cooperation on security and terrorism, education and science risked being left up in the air if no detailed agreement had been reached on future EU-UK relations.
What did each side want from post-Brexit ties?
The UK sought a free trade deal with maximum independence from EU rules. The EU's priority is to protect the integrity of its projects and to ensure the UK has no unfair competitive advantage in the future.
European Union leaders called at the outset of the negotiations for an “ambitious” wide-ranging agreement — subject to conditions. The EU wanted one comprehensive treaty covering everything, whereas the United Kingdom sought a simpler free trade deal and separate agreements on other matters.
Boris Johnson’s nationalist government — with no allies among the EU27 countries over Brexit — was seeking a far more distant, independent relationship with the EU than the one sought under the previous UK prime minister, Theresa May.
And though Johnson described the new deal as "Canada-style", Brussels had always stressed that the UK’s geographical proximity to the EU, and degree of economic integration with Europe, meant the same rules cannot apply.
Although the talks involved elaborate technical detail, both sides had over-arching political objectives. The UK wanted to make sure its European ties did not compromise its new independence; the EU needed to show that life inside the bloc is better than outside, and consistently said the UK could not "cherry-pick" benefits without obligations.
Divorce deal pledges in the Political Declaration
The EU and the UK signed up to various assurances on future trade competition and other matters. This included a commitment to a "level playing field" covering issues such as state aid, social and workers' rights, the environment and climate change.
These engagements came in the Political Declaration on the shape of future EU-UK relations, negotiated as part of the divorce deal agreed in the autumn of 2019, paving the way for the UK's departure from the bloc. The document provided a framework designed to form the basis for a future trade agreement.
The declaration related to a future EU-UK economic relationship where the UK opted for a Free Trade Agreement (FTA). But in return for zero tariffs and quotas, the UK made "robust commitments" to ensure "open and fair competition".
However, the document was legally non-binding — as opposed to the divorce deal's Withdrawal Agreement, on the terms of the UK's departure, which has the force of an international treaty. Critics were wary that the commitments might not be watertight — especially given the Johnson government's avowed intention to diverge from EU rules and forge an independent trading path.
Some observers argued that negotiations over future ties risked being much more complicated and harder to resolve than the terms of the divorce deal. The stalemate resulting from the talks in 2020 appeared to bear this out — until in the end a deal on the future relationship was struck in the nick of time.
However, its application in the years to come is bound to involve many more negotiations and, inevitably, disputes.
Read more:Brexit trade talks: Key terms explained
Deadlock over competition and fishing rights
These were the bane of the negotiations and looked for a long time like they were impossible to resolve. Throughout the talks, the EU's chief negotiator Michel Barnier repeatedly said the UK had failed to engage on a commitment to respect the "level playing field" in competition, while his British counterpart effectively accused Brussels of moving the goalposts.
Key sticking points included EU access to UK fishing waters and state subsidies.
The EU wanted to ensure that British firms could not undercut the bloc’s environmental or workplace standards. It was also determined to make a trade deal conditional on securing agreement on "state aid" rules, to prevent the UK from distorting competition by pumping public money into domestic industries.
Barnier's British counterpart David Frost had previously accused Brussels of unfairly trying to tie the UK into EU rules and standards, arguing that EU demands on fishing were incompatible with UK sovereignty.
The EU chief negotiator was equally disparaging over the UK's stance on matters such as governance, law enforcement, transport and sustainable development — adding that the British seemed to misunderstand the consequences of leaving the EU's Single Market and Customs Union.
Over transport rights, Barnier criticised London for wanting certain rules such as driving time and rest periods to be waived for British lorry-drivers while on European roads, but for access to be the same as that granted to workers from EU member states.
Trade talks timeline: Months of stalemate on future EU-UK ties
Both sides outlined sharply contrasting positions as they flexed their muscles in advance of the talks. Setting out the EU's position, Michel Barnier said there could be no trade deal unless Britain agreed to the "level playing field" commitment and did not undercut EU regulations.
But during the pre-talks period Johnson, other ministers and officials, all highlighted the UK's stance: that being able to diverge from EU rules and standards was the essence of Brexit and the UK’s “new footing as an independent sovereign nation”.
Coronavirus puts a spanner in the works
A first round of talks in March was followed by a six-week suspension amid the coronavirus outbreak, which totally overshadowed the process as it developed into a full pandemic. Key figures including Barnier and UK Prime Minister Boris Johnson were struck at various stages by COVID-19.
Three further rounds took place by video link instead of face-to-face talks, a step seen as necessary but unsatisfactory given the detail involved and the dozens of negotiators on each side.
At each stage, both sides expressed frustration at the lack of progress. At the end of the second round of talks in April, Barnier effectively accused the UK of dragging its feet.
He used similar language at the end of a third round of discussions in mid-May, accusing the UK of a lack of ambition. His British counterpart David Frost agreed that little progress had been made, accusing the EU of adopting an ideological approach.
After the fourth round in early June, the EU negotiator's language was starker than ever. Barnier said no significant progress had been made towards a deal, accusing the UK of backtracking on commitments. Frost said progress had been "limited" and regretted the remote format.
In June 2020, both sides agreed to intensify talks over the summer, after extremely sluggish progress during the first few months of negotiations.
Although large differences remained on fundamental issues such as competition and fishing rights, late July brought signs that both the UK and EU are willing to compromise in some areas -- leading to hope that a deal could be struck.
But optimism was short-lived: after a seventh round of talksin August brought "little progress", Barnier complained that "we are wasting valuable time".
In early September Boris Johnson threatened to walk away from the talks if no breakthrough was achieved by the time of an EU summit in mid-October. The beginning of that month saw both sides using similar language to describe the ongoing stalemate, despite "positive developments" in some areas.
The tone subsequently turned more conciliatory: Barnier said agreement was "within reach" if both sides compromised and talks resumed amid a media blackout. However, serious differences remained as another round ended in early November.
After many missed deadlines the two sides continued to negotiate right through December, even though time had run out for a conventional ratification process.
Transition extension is ruled out
The divorce agreement allowed for a two-year extension of the transition period to give more time for negotiation, with an end-of-June deadline for a decision on whether to invoke it. Both sides have agreed however that there will be no prolongation, the EU having accepted the UK's opposition to it.
Despite the coronavirus pandemic, Britain consistently ruled out any extension having legislated to that effect — although the full effect of the global health and economic crisis in the coming months remains to be seen.
Some voices had called on the UK to seek an extension: they included the head of the International Monetary Fund (IMF) Kristalina Georgieva, the European Parliament's largest group the European People's Party, and the anti-Brexit campaign group Best for Britain.
Critics said the shorter deadline provided nowhere near enough time to conclude a deal embracing all aspects of future EU-UK relations. One possibility evoked was for a simpler, more “bare-bones” trade deal to be struck, leaving the detail of other policy areas to be sorted out later.
UK plan to breach EU divorce deal
In September 2020 the Johnson government sparked a furore with its bombshell UK Internal Market Bill, further souring UK-EU relations, casting a shadow over the talks on future ties. The EU launched legal action.
The bill contained measures which would have overriden sections of the Northern Ireland Protocol — part of the UK-EU divorce deal that has the force of international law (see Brexit Divorce Deal section below). The British prime minister described the bill as a legal "safety net" to protect the UK's integrity.
On December 8, 2020 the UK said it had agreed to withdraw the contentious measures when agreement was struck with the EU on implementing the arrangements for Northern Ireland contained in the divorce deal.
However, the episode raised fundamental questions over trust — and reinforced EU resolve to ensure that a deal on future relations included a robust mechanism to enforce it.
BREXIT DIVORCE DEAL: the UK's exit terms
The UK's departure from the EU on January 31, 2020 took effect under the terms of the revised divorce agreement struck by London and Brussels in October 2019.
An ill-fated previous version negotiated under Theresa May's UK premiership met stiff opposition in the British parliament which repeatedly rejected it. The new accord was negotiated by her successor, Boris Johnson, whose subsequent election victory ensured its rapid ratification.
The deal consists of a Withdrawal Agreement on the terms of departure, accompanied by the Political Declaration on future ties (see above).
The deal also established the transition period which came into effect upon the UK’s departure and runs until December 31, 2020. During this period many existing arrangements remain in place.
The Withdrawal Agreement: a binding treaty
The revised Withdrawal Agreement kept many of the provisions in the deal previously negotiated by Theresa May's government.
The divorce terms contained in it cover matters such as the UK's financial settlement, provisions for Northern Ireland, and citizens' rights: safeguards for the rights of EU nationals living in the UK, and Britons living on the continent.
It establishes a mechanism for calculating the amount of money the UK owes the EU to settle its obligations. No figure is mentioned but estimates have put it above €40 billion. It includes contributions to be paid during the transition period.
The agreement also protects residency and social security rights for EU nationals living in the UK and Britons in the EU, and maintains freedom of movement until the end of the transition period. People already resident will be allowed to stay afterwards and apply for permanent residence after five years.
The main change from the deal negotiated by Theresa May's government is that the controversial Irish "backstop" contained in the previous accord (see below) — to keep an open border on the island of Ireland — is scrapped in the revised agreement.
The divorce terms came into force when the UK left the EU at the end of January under the ratified deal, and have the force of an international treaty.
Arrangements for Northern Ireland
Brexit means that the border between Northern Ireland (part of the UK) and the Republic of Ireland (part of the EU) — one of the most politically sensitive frontiers in the world — becomes the European Union's only land border with the United Kingdom. All sides agree this must remain open, but the historically sensitive and complex issue bedevilled the divorce talks.
The arrangements in the revised Northern Ireland Protocol in the divorce deal, as in the previous version, are designed to avoid a hard border — such as border posts — and protect the cross-frontier economy.
As of January 2021 and the end of the transition period, Northern Ireland has left the EU's Customs Union with the rest of the UK, which wants to pursue an independent trade policy. But in practice, it still follows EU customs rules and is subject to EU oversight.
The North remains aligned with some aspects of the EU's Single Market — and applies EU law on VAT (Value Added Tax) rules.
Northern Ireland is guaranteed "unfettered access" to the UK's internal market. But the rules mean there is effectively a new regulatory divide in the Irish Sea, especially concerning goods sent from Great Britain to Northern Ireland.
Customs and regulatory checks will not be carried out on the island of Ireland, but at ports. The UK government accepted that there would be some controls on goods, backtracking on Boris Johnson's previous insistence that there would be no checks.
In December 2020, the EU and the UK struck agreement on details for implementing the arrangements for Northern Ireland contained in the divorce deal. As part of the accord, the British government agreed to ditch a controversial plan to override parts of the original deal which would have breached international law (see above).
Goodbye to the backstop
The revised protocol on Northern Ireland replaced the plan in the previous, rejected withdrawal deal known as the backstop. In the absence of a trade deal or an alternative solution, Theresa May's idea was for the whole of the UK to remain in a customs union with the EU, while Northern Ireland would be aligned even more closely with EU rules. The backstop's removal means this arrangement will no longer happen.
The revised agreement has similarities with an original EU proposal for a Northern Ireland-only backstop — which was rejected by May's government — but is more complex, and has one key difference in that legally, Northern Ireland remains in the UK customs union.
The accord deals with the issue of Northern Irish consent for these changes: Northern Ireland's assembly will be able to decide on whether to keep the new arrangements — but only four years after the transition period.
HOW WE GOT HERE: Brexit follows decades of UK soul-searching over Europe
The United Kingdom's place in Europe — and vice-versa — is an issue that arguably was never properly resolved after the Second World War, and came to a head with the Brexit referendum.
Many in the UK, especially in England, have always been sceptical of the political pan-European project revered by many on the continent. The antagonism towards the EU that surfaced during Margaret Thatcher's premiership in the 1980s has been followed by decades of hostile media coverage, especially in British tabloids.
At the heart of the debate in the UK is the balance to be struck between two objectives: a desire for independence, sovereignty and autonomy against the need to retain access to European markets, which, the EU insists, means respecting its rules and committing to fairness in competition.
The turmoil in the British domestic political scene has cut across party lines. Internal party divisions have affected both the UK government and opposition. The ruling Conservative party in particular has long been riven between Eurosceptic and Europhile factions.
A history of UK-EU tension
Check out our series on the history of the United Kingdom's complicated relations with the European Union:
- Part 1, 1973-1990: Je T'aime, Moi Non Plus
- Part 2, 1990-2004: I'd Do Anything For Love
- Part 3, 2004-2016: Should I Stay or Should I Go
- Part 4, 2016-2017: I Will Survive
- Part 5, 2017-2019: Never Can Say Goodbye
- Brexit Timeline 2016—2020: key events in the UK's path from referendum to EU exit
Theresa May's deal repeatedly rejected by UK parliament
The referendum result in June 2016 prompted the resignation of Prime Minister David Cameron — who had led the campaign to keep the UK in the EU. He was replaced the following month by Theresa May, who in March 2017 triggered the EU's Article 50 — giving formal notification of the UK's intention to leave — two years later on March 29, 2019.
London and Brussels then negotiated a withdrawal deal over an 18-month period, which was finally agreed in November 2018 and approved by the 27 other EU governments.
The former prime minister insisted her negotiated withdrawal agreement was in the national interest and there was no viable alternative. She argued that it delivered on the referendum result: an end to free movement, an end to huge UK payments to the EU, and an exit from the unpopular EU structures on farming and fishing.
However, May had been severely weakened at home by an ill-judged snap election in June 2017 which wiped out her majority in parliament. Her government struggled on thanks to a deal with Northern Irish unionists. But the EU agreement brought hostility from both opponents and supporters of Brexit, including many in the ruling Conservative Party.
Thanks to an alliance of forces, the EU divorce deal was rejected three times by the UK parliament between January and March 2019 — causing Brexit to be delayed and leading eventually to May's resignation and her replacement by Boris Johnson.
Derailed by the backstop
To guarantee an open border, the backstop envisaged the UK remaining in a "single customs territory" with the EU, in the absence of a free trade deal or an alternative solution. It proved to be a major stumbling block in the negotiations.
Eurosceptic critics, including the Conservative anti-EU European Research Group (ERG), suspected it would have kept the UK strapped permanently to EU trade policy. EU sources pointed out that the UK-wide mechanism in the withdrawal agreement was included at the UK’s request, to avoid splitting off Northern Ireland from the rest of the UK.
Northern Ireland's Democratic Unionist Party (DUP), on whose support the May government depended, has always vehemently opposed any move it believes might separate Northern Ireland from the rest of the United Kingdom. Under the backstop, as set out in May's deal, Northern Ireland would stay aligned to some EU rules.
Revisions fail to stop defeats
As the clock ticked down towards the original March 29 deadline, the UK and the EU said they had agreed a revised Brexit deal following weeks of deadlocked talks between London and Brussels.
EU27 leaders had refused to alter the text of the withdrawal agreement. But Theresa May said she had secured legally-binding changes over the backstop’s application. The British parliament had voted to seek “alternative arrangements”.
The parliamentary deadlock prompted moves by MPs from different parties to wrest control of the Brexit process and allow a series of "indicative votes" to explore alternative solutions to the government's deal. But there was no majority for any particular solution, other than an opposition to no-deal.
Theresa May's Brexit battles
Theresa May always struggled to keep the pro and anti-European wings of the Conservative Party on board with her Brexit plans.
Her doomed UK-EU divorce deal represented a compromise. But the blurring of several of her so-called "red lines" on the limits of EU power sparked fury within her divided Conservative Party. As negotiations with Brussels brought more UK concessions, a string of government resignations followed.
After the 2017 general election, which left the Tories severely weakened in parliament, hostility amid their own ranks to any moves towards a "softer" Brexit restricted May's room for manoeuvre.
Eurosceptics including the DUP strongly opposed her Brexit plan and the subsequent agreement, with many calling for the UK to leave the EU with no deal. In early 2019, the Tories in particular haemorrhaged support to the new hardline Brexit Party.
Equally, several pro-EU MPs also opposed a deal which, in their view, would leave the UK worse off than it had been inside the bloc. Some joined calls from opposition parties for a second referendum. Both the Conservatives and opposition Labour parties suffered defections of some MPs to a new pro-EU centrist party.
Amid the parliamentary deadlock, pressure from Tory Europhiles obliged the prime minister to open the door to a Brexit delay — and engage in cross-party talks, which collapsed after a few weeks.
Theresa May's fate was sealed after she revealed a fourth plan for getting her thrice-rejected Brexit deal through parliament. She tweaked the legislative package and crucially opened the door to a possible confirmatory referendum — a move which angered many in her party and sparked another government resignation.
Brexit delay brings European election electroshock
In the wake of the repeated parliamentary defeats for the EU divorce deal, the House of Commons twice forced the British government to seek to delay Brexit. In April 2019 EU national leaders met for a special European Council summit and agreed to a six-month "flexible extension" to the UK's departure from the bloc, with a new exit date set for October 31 — or earlier if its parliament approved the original withdrawal deal.
But relief at avoiding a disruptive no-deal exit was tempered by renewed uncertainty and frustration for businesses and people — especially for EU and UK expats.
The extension of the UK's EU membership also forced the country to take part in the European Parliament elections in May — and send 73 newly-elected MEPs to Strasbourg in July.
Nigel Farage's new Brexit Party, which advocates leaving the EU without a formal agreement, came top of the European vote. But there was a strong showing from pro-EU parties, in particular, the Liberal Democrats, who wanted to reverse Brexit altogether.
Britain's two main parties — the Conservatives and the Labour opposition — were severely punished by voters. Many Conservatives are furious at the failure to “deliver Brexit”, while Labour was accused of sitting on the fence.
The results indicated that opinion in the UK had become still more polarised over Brexit.
'Get Brexit done': PM Johnson launches new drive for EU exit door
The prolonged period of turmoil in British politics came to a head when Theresa May — who failed to get her EU divorce deal through parliament — became the latest in a long line of Conservative prime ministers to be brought down by Europe.
The UK's stance towards Brexit took on a distinctly harder edge when Boris Johnson entered Number 10 Downing Street in late July, 2019. The former foreign secretary and London mayor took over the reins after winning the Conservative Party leadership contest.
He signalled immediately a reinvigorated drive to take the UK out of the EU on October 31 — "no ifs or buts" — raising the likelihood that the country would leave the EU without a withdrawal deal.
The summer and autumn of 2019 saw the UK government significantly ramp up its no-deal preparations — since stood down — with more funds promised. The Conservative conference in Manchester had a new slogan, “Get Brexit done” — which has echoes of the “take back control” rallying cry of the “Leave” campaign during the 2016 referendum campaign.
There was further turmoil in the British parliament, where there was stiff opposition to a "no-deal Brexit". The government lost numerous votes in the House of Commons, and lost its thin majority. Several Tory rebels were expelled for opposing Brexit strategy.
Johnson suffered a humiliating defeat when the country’s highest court ruled that his government had acted unlawfully by suspending parliament.
In the end Boris Johnson was forced to compromise over Northern Ireland to win a revised deal. UK law obliged the prime minister to seek a Brexit delay from the EU, which was duly granted.
Boris Johnson seals new Brexit deal with EU
Opposition parties granted Boris Johnson his much-sought general election after the threat of an imminent no-deal Brexit in October was overcome.
In the absence of parliamentary approval for his renegotiated deal by October 19, the prime minister was obliged by law to seek a delay of three months from the European Union.
On October 29 the European Council President Donald Tusk confirmed that the EU had formally adopted the latest extension of the UK's membership until 31 January 2020 — with the option of an earlier departure if the renegotiated divorce deal was ratified.
The delay put paid to Boris Johnson's vow, repeated many times, that the UK would leave the EU on October 31.
New Brexit deal is struck — but UK bill is derailed
The EU and the UK announced on October 17 that they had reached agreement on a revised exit deal. It came on the day of a crucial EU summit and followed a period of intensified talks. The accord was swiftly given the green light by EU national leaders.
The deal altered previously-negotiated arrangements for Northern Ireland, and envisaged a clearer break for the UK with the EU than the accord struck by Theresa May.
Boris Johnson became prime minister in late July, but it was early October before his government submitted a detailed proposal for a new divorce deal to Brussels. He then threw out its controversial plan for Northern Ireland to reach a compromise.
A bill to implement the new deal passed its first parliamentary hurdle, but was shelved by Johnson himself when MPs rejected the government's fast-track three-day timetable to get it passed. Many felt far more time was needed to scrutinise measures that will determine the UK's relations with Europe for years to come.
How did Johnson reach a revised deal with the EU?
In a nutshell, Boris Johnson made major concessions over Northern Ireland.
Out went the UK's previous proposals — much vaunted by Brexit supporters — for "alternative arrangements" including technological solutions to keep an invisible border. Instead, Johnson has agreed to a different status for Northern Ireland compared to the rest of the UK — accepting a plan very close to one the EU originally proposed.
The EU also gave ground, re-opening the withdrawal agreement it had always said was sacrosanct. Dublin and Brussels agreed to replace the controversial Irish border backstop that had plagued Brexit talks for months, and opened the door to a possible time-limit on border safeguards with a new consent mechanism.
However, Johnson's change of tack came at a price: Northern Ireland's Democratic Unionist Party (DUP), until then an ally of the government, said it could not support proposals that would create a "border in the Irish Sea".
Arrangements for Northern Ireland were a key sticking point throughout negotiations ever since the UK triggered the formal Brexit process in March 2017. Behind the details over trading arrangements are fundamental questions concerning identity. The possibility of new borders — between Northern Ireland and either the Irish Republic, or Great Britain, or both — is hugely problematic in a region with a troubled past.
Tory election win ends long Brexit deadlock
The UK finally broke the long-standing Brexit stalemate following the snap general election on December 12, 2019, which brought a crushing victory and 80-seat parliamentary majority for Boris Johnson's ruling Conservative Party.
The Tories campaigned on a promise to leave the EU by the end of January, and the prime minister's campaign slogan of "Get Brexit done" evidently struck a chord with voters. The 80-seat margin provided an ample cushion to put the UK's exit into effect.
The main opposition Labour Party suffered its biggest defeat since 1935. Under leader Jeremy Corbyn — since replaced by Sir Keir Starmer, the party's former Brexit spokesman — the party's policy was much criticised. Its plan if elected was to renegotiate a Brexit deal which would then have been put to the public in a second referendum.
The pro-EU Liberal Democrats won fewer than a dozen seats — despite increasing their share of the vote — as the "Remain" vote was split. The party's campaign pledge to stop Brexit altogether if elected proved unpopular with voters.
The Scottish National Party (SNP) which also campaigned to "stop Brexit", but via a second public vote, won the vast majority of seats north of the border with England. Across the Irish Sea, anti-Brexit votes also came to the fore as Northern Ireland elected more Irish nationalists to the UK parliament than pro-British unionists.
EU welcomes 'clarity' as Brexit becomes a certainty
Throughout 2019, the fear for many on both sides of the English Channel was that the UK could "crash out" of the EU without an agreed deal on either the terms of the divorce or the future relationship (see 2019 "No deal revisited" section below).
But the threat of such a "no deal" exit in January 2020 vanished with the UK election result in December 2019, which saw Boris Johnson's Conservative government re-elected with a large majority.
EU leaders welcomed the "clarity" brought about by the election result. Any remaining uncertainty was removed after the divorce deal was ratified by both the British and European parliaments — legal requirements for its terms to take effect.
The European Parliament passed the deal on January 29, 2020 by a large majority, despite expressing concerns over the rights of Britons living in the EU, and especially the rights of EU citizens resident in the UK.
In the UK, the Conservatives' election victory ensured that the legislation to implement Brexit was duly passed by parliament, receiving royal assent on January 23.
The UK went on to leave the EU on Friday, January 31 at midnight CET (11pm UK time) under a ratified divorce agreement. Its provisions on the exit terms — on the financial settlement, citizens' rights, and Northern Ireland — are incorporated into a binding international treaty.
'No-deal' revisited: Fears of economic damage and disruption in 2019
Well before the coronavirus pandemic caused havoc, in the run-up to Brexit many political leaders, institutions, companies and individuals warned that a no-deal departure would bring severe disruption and economic damage on both sides of the English Channel — with the UK being hit worse than the EU.
However, Brexiteers dismissed “Project Fear” forecasts and some argued that the UK could survive perfectly well under World Trade Organisation (WTO) rules.
Although the UK has since left the EU under the terms of the divorce deal, the concerns over failure to reach a deal on trade and other matters concerning future ties have echoes today.
Government documents, published in early September 2019 and codenamed "Operation Yellowhammer", confirmed a grim assessment of the potential impact of a no-deal Brexit on October 31. Based on the government's own preparations for a "worst case" scenario, they contained warnings of possible food, medicine and fuel shortages.
The heightened uncertainty amid a year of British political turmoil in 2019 twice forced the UK and the EU — as well as people and businesses on both sides of the English Channel — to step up no-deal preparations, as the Brexit process dragged on without formal approval for an exit deal.
Theresa May's government published a series of papers — some updated under her successor — advising UK citizens and businesses on the consequences and how to prepare for no-deal. It said the EU would treat the UK as a "third country".
British economic sectors reliant on close, smooth arrangements with Europe warned of the dangers of new costs and restrictions being imposed overnight. Among those sounding alarm bells were manufacturing industries — including the car industry, food and drink, chemicals and pharmaceuticals – as well as aviation, the health service, tourism, and financial services. There were also warnings over farming and fishing — despite strong support for Brexit from within these two sectors.
In August 2019, after the Bank of England lowered its growth forecast for the UK post-Brexit, its governor Mark Carney warned that in the event of no deal the economy would suffer an instant hit, prices would rise and the pound would fall, and even large profitable industries would become "uneconomic".
In April 2019, a leaked letter by the government's most senior civil servant warned of an economic recession, food price rises, a severe impact on Britain's security services, police forces and legal system, and a return to direct rule by the UK government in Northern Ireland. In early August a leaked government document contained similar warnings.
In November 2018, two major reports by the UK Treasury and the Bank of England assessed the potential damage to the British economy of various Brexit scenarios.
In an assessment of EU preparations for no-deal published in July 2019, the UK House of Commons Library described the Commission's programme as one of "damage limitation" to protect the EU27 countries.
How does the European Union work?
The EU originally developed after World War Two, with the aim of promoting economic co-operation and trade between countries to stop them from going to war again. Its members' economies are now integrated around a single market allowing the free movement of goods, people, services and capital.
Nineteen of the 27 member states use a single currency, the euro. The EU has its own institutions and passes laws affecting many issues across the union.
It highlights the benefits of membership as securing peace, promoting freedom and prosperity as part of the single market, safeguarding food and environmental standards, consumer benefits, protecting human rights, and enhancing Europe's global power.
The European Council is led by its president and is made up of the national heads of state or government, as well as the president of the Commission. It sets the EU's overall political direction but has no law-making powers.
Read more: What does the European Council do?
The European Commission promotes the EU's general interest. It is made up of Commissioners, one from each member state, nominated by national governments. It proposes and enforces laws and implements EU policies and its budget.
Read more: What does the European Commission do?
The European Parliament is the only institution directly elected by its citizens, and represents them. It also has legislative, supervisory and budgetary responsibilities.
The UK's departure brought another headache for the EU, in the shape of a hole in its budget for the next few years.
Despite this and the devastating effect of the pandemic, a 7-year €1.8 trillion budget and coronavirus recovery package was approved by the European Council and European Parliament in December 2020.