The Beginning
It starts with an election pledge.
In 2013, then-prime minister David Cameron promises to take the issue of Europe back to the people if the Conservatives win the next election.
In its 2015 manifesto, the party says people's concerns over Britain's membership of the European Union have been ignored, and promises them an in-out referendum by the end of 2017 at the latest.
For too long, your voice has been ignored on Europe. We will give you a say over whether we should stay in or leave the EU with an in-out referendum before the end of 2017.
Europe had bedevilled Tory leaders for decades - think of the problems experienced by Margaret Thatcher and John Major. Having once promised to stop his party "banging on about Europe", Cameron finds the issue creeping back up the political agenda as his time in Downing Street wears on.
A key driver of his decision to promise a referendum is the rise of UKIP, then led by Nigel Farage. The eurosceptic party was enjoying strong opinion poll ratings, so the thinking was that Cameron wanted to halt the rise of UKIP and definitively settle the European question.
The Conservatives win a surprise majority in the election, bringing to an end the coalition government with the Liberal Democrats and setting Britain on a path that will eventually result in Brexit.
Within months of returning to Downing Street, Cameron embarks on a much-trumpeted tour of Europe in an attempt to renegotiate Britain's relationship with Brussels.
He returns with what he thinks is a good deal, although debate rages to this day as to whether Cameron could - and should - have demanded more.
On the steps of Downing Street in February 2016, he announces the EU referendum will be held on 23 June that year and pledges to campaign for Britain to stay in a reformed EU.
The Campaign
A four-month campaign sparks a fierce debate about the best course forward for Britain.
The official Remain campaign is called Britain Stronger In Europe, and is backed by Cameron as well as a majority of Tory MPs and government ministers. Labour, the Liberal Democrats and the Scottish National Party also argue in favour of staying in.
The crux of the Remain argument is that Brexit is too risky. Voters will be taking a huge gamble that will have irrevocable consequences, they argue.
Stronger In warns that Britain's economic prosperity will be put in peril, with then-chancellor George Osborne infamously claiming he will be forced to cut public spending and hike taxes in the event of a Leave vote, which he claims will cause a year-long recession.
People are told they will feel the squeeze on their household budgets. The Remain campaign says prices on a weekly food shop are lower because of EU membership; claim holidays in Europe will cost £230 more outside of the EU; and also suggest the era of free healthcare on the continent will end with a Leave vote.
There are also predictions of hundreds of thousands of job losses; a decline in British influence on the world stage; and the potential for Britain's security to be weakened.
To opponents, this is pure hysteria. Project Fear.
Those in the Remain camp argue they are setting out the significance of the decision voters are about to make.
The Vote Leave campaign is very much considered the underdog when Cameron calls the referendum.
Within hours of the announcement, ministers like Michael Gove, Iain Duncan Smith, John Whittingdale, Theresa Villiers and Priti Patel declare for Leave.
The backing of Mr Gove, a friend of Mr Cameron, is seen as significant, but it is the events of the following day that spark the campaign into life.
Boris Johnson has been on the fence about which side to take, but he eventually gives his backing to the Leave camp. He brings unrivalled star-power and charisma to the Brexit cause. Westminster observers see it as huge big blow for Cameron.
The essence of the Leave message is distilled into its campaign slogan: "Take Back Control."
It argues a Britain free of the shackles of Brussels can take back control of its money, laws and borders. All that cash sent to Brussels coffers can be spent in this country, in areas in dire need of funding.
Like the NHS.
Vote Leave's claim - plastered on the side of its campaign bus - that we send £350m a week to the EU and that this could be spent on the health service captures the public's imagination.
It is a masterstroke of messaging, but the claim is labelled "potentially misleading".
Why? Because it doesn't take into account things like the rebate Britain receives from the EU.
Brexit supporters say Britain will be able to take back control of its borders, end free movement from the EU and implement its own immigration system better suited to the country's needs.
It also argues Britain will be able to go out into the world and strike tailored free trade deals with other nations.
The Vote
Most polls during the campaign suggest Remain is on course to win, so events in the early hours of 24 June leave many in Westminster surprised.
The first indication that something seismic is happening comes when Sunderland votes overwhelmingly to Leave - by a much larger margin than expected.
Leave.eu supporters celebrate in Sunderland
By 6am a new dawn has broken. Britain has voted to leave the EU. A total of 52% of voters back Brexit, compared to 48% who opt to Remain.
As the markets crash and the public digests what has happened, a stunned Cameron has to deliver the speech he never thought he would have to give.
Having staked his premiership on the result, Cameron appears outside Downing Street within hours and announces his resignation.
I was absolutely clear about my belief that Britain is stronger, safer and better off inside the European Union and I made clear the referendum was about this and this alone - not the future of any single politician including myself. But the British people have made a very clear decision to take a different path and as such I think the country requires fresh leadership to take it in this direction.
Cameron says he will leave office by October, firing the starting gun on a Tory leadership contest that has a number of twists and turns.
New PM
As the star of the Brexit campaign, Johnson is the early favourite. But a remarkable course of events - like one-time ally Gove deciding to withdraw his support and stand himself - makes the former London mayor pull out of the race.
Theresa May largely keeps a low profile during the campaign, save for one nuanced speech where she argues, on balance, for staying in.
As the leadership race gets under way, she overwhelmingly wins the first two ballots of Tory MPs. Party members are then set to choose between Mrs May and Leave-supporting minister Andrea Leadsom.
However, Mrs Leadsom drops out of the race after she makes controversial comments in a newspaper interview. She appears to suggest the fact that she is a mother makes her a better choice to be leader than the childless May.
Two days after this, on 13 July, May officially succeeds Cameron as prime minister.
Article 50
As soon as May takes office, she faces calls to invoke Article 50 and formally start the Brexit process. She initially holds off, as debate continues within and without her government as to what the best strategy is.
After fleshing out her approach during her first few months in office, including saying Britain will leave the EU's single market and customs union, May moves to trigger Brexit.
There is a slight hiccup when philanthropist Gina Miller goes to court to argue that the prime minister can't invoke Article 50 without the backing of parliament. Miller wins her case, and two months later, the Supreme Court upholds that decision.
At the end of March, May is able to invoke Article 50, following her clearing her Brexit bill through the Lords and Commons. Having earlier resisted pressure from parliament, May pledges MPs and Lords will be able to vote on the final deal.
This is an historic moment from which there can be no turning back. Britain is leaving the European Union. We are going to make our own decisions and our own laws. We are going to take control of the things that matter most to us. And we are going to take this opportunity to build a stronger, fairer Britain – a country that our children and grandchildren are proud to call home. That is our ambition and our opportunity. That is what this government is determined to do.
Invoking Article 50 leads to the beginning of the two-year process of negotiations and meetings to pave the way for Britain's official departure date, 29 March 2019.
The clock is ticking.....
(Not another) General Election
Three weeks after invoking Article 50, and feeling confident, May calls a snap general election - it was a sharp U-turn. She says Britain needs strong leadership to chart a course through Brexit - and an election is the only way to deliver this. It is clear the PM wants to win an increased majority and gain a mandate for her leadership.
After several voting opportunities in just a few short years, Brenda from Bristol captures the mood of the nation when she is asked by a reporter what she thinks of the prime minister's decision to call an election. Her reply of "you're joking... not another one!" goes viral and is commemorated as #BrendaDay each year.
Division in Westminster will risk our ability to make a success of Brexit and it will cause damaging uncertainty and instability to the country. So we need a general election and we need one now, because we have at this moment a one-off chance to get this done while the European Union agrees its negotiating position and before the detailed talks begin.
The election is held on 8 June 2017. The result is a disaster for May.
The Conservatives lose their Commons majority and are forced to continue in government as a minority administration. May agrees a confidence-and-supply arrangement with Northern Ireland's Democratic Unionist Party, which in exchange gets £1bn in extra funding for Northern Ireland.
Negotiations finally begin
After May’s questionable election decision and the triggering of Article 50, Brexit negotiations can finally get going. On 26 June 2017 they begin, a year after the referendum. A week before, David Davis, then Brexit secretary, goes to Brussels to set out the timetable with the EU, scheduling four-week segments in which key areas will be discussed.
There are talks for about three days at a time every month through the rest of 2017. Some of the key sets of negotiations include the September talks, where the guidelines on the Irish border are first laid out. Both sides state their commitment to maintaining the Good Friday Agreement and a continuation of the common travel agreement.
Phase one negotiations run from June 2017 until March 2018, when the EU and Britain come to something of a sticking point over the Irish border. Phase two negotiations partially overlap with the end of phase one, as they run from December 2017 until March 2018. They cover the transitional phase of Britain leaving the EU as well as the framework on the future relationship once Britain is completely out of the EU. Phase three negotiations start in July 2018 and cover trade relations.
While negotiations are ongoing, the Electoral Commission finds that the official Leave campaign broke electoral law and refers it to police. It finds the campaign exceeded its legal spending limit of £7m by almost £500,000.
The allegations centre around a £680,000 donation Vote Leave made to the youth-focused campaign group BeLeave, something which the Electoral Commission says should have been declared.
In the aftermath of the Electoral Commission's verdict, Downing Street makes clear the prime minister does not think the development calls the validity of the referendum into question.
Chequers Plan
In June 2018, the EU Withdrawal Bill becomes law. The flagship legislation will allow EU law to be transferred into UK law as part of the Brexit process. But if May thinks this will be an indication of plain-sailing ahead, she is mistaken.
In early July, May calls a meeting at Chequers, her country retreat, to gain cabinet backing for her Brexit blueprint. The resulting document becomes known as the Chequers Plan and it sets out what she would like the UK's future relationship with the EU to look like.
Despite talk of potential resignations ahead of the showdown, every member of the PM's cabinet signs up to proposals.
But the unity last a matter of hours. First David Davis walks away from his role as Brexit secretary, saying May's approach is giving too much ground to the EU.
Then, a little more than 12 hours later, Boris Johnson follows suit. In his letter outlining his reasons for quitting as foreign secretary, Johnson says the PM's strategy would reduce Britain to "the status of a colony".
For many in her party, the Chequers plan keeps Britain too closely aligned to EU rules and regulations, and doesn't deliver fully on the will of the voters expressed in the referendum to "take back control".
Then Donald Trump comes to town. In an unhelpful intervention, the US president says in a newspaper interview that Chequers will "probably kill" any hopes of a trade deal between the two countries. In a news conference, Trump denies making the claim, even as an audio recording of the interview is published.
If they do a deal like that, we would be dealing with the European Union instead of dealing with the UK, so it will probably kill the deal.
These developments lead to talk of a potential confidence vote in the PM. But despite the resignations and bombshell intervention from Trump, May remains in office.
The end in sight?
Fast forward to the autumn. Dominic Raab is Brexit secretary, a man confident that a deal can be delivered in good time. At the end of October, he says the end is in sight. Following a number of false dawns, a draft agreement with the EU is reached. After what feels like months and months of talking and little else, events start to move quickly.
Ministers are summoned to read the details of the deal on the table, as Brexiteers react with fury to the agreement's rumoured contents. The following day, a marathon five-hour cabinet meeting sees May's top team sign off on the deal.
The PM hails a "decisive step forward", but as has so often been the case during her premiership, problems aren't too far away. Raab quits, telling May the draft agreement is a "very real threat to the integrity of the United Kingdom" because of its implications for Northern Ireland.
Above all, I cannot reconcile the terms of the proposed deal with the promises we made to the country in our manifesto at the last election. This is, at its heart, a matter of public trust.
Work and Pensions Secretary Esther McVey follows Raab out the door, and as the hours tick by it looks like the PM is facing an imminent confidence vote in her leadership. Such expectations are heightened when Jacob Rees-Mogg, considered a standard bearer for the Brexiteer cause, announces he has submitted a letter of no confidence in May. A difficult day also sees the DUP make clear it can't support the agreement, as opposition to it hardens.
The PM puts on yet another show of defiance, declaring in a Downing Street news conference that she is "going to see this through". She compares herself to her cricketing hero Geoffrey Boycott - someone who "stuck to it" and "got the runs in the end".
Still at the crease, May pushes on. A vote on the deal is set for 11 December, setting up the mother of all parliamentary showdowns.
Or so we thought. Amid indications she is on course for a heavy defeat, the PM decides to delay the vote and announces she will seek further assurances from Brussels over the Irish border backstop.
From listening to those views it is clear that while there is broad support for key aspects of the deal, on one issue, the Northern Ireland backstop, there remains widespread and deep concern. As a result, if we went ahead tomorrow it would be rejected by a significant margin.
For many Tory MPs, this is the final straw. A flurry of no confidence letters are submitted, enough to trigger a vote in May's leadership. In a surprisingly quick turn of events, the announcement is made early in the morning and the contest held that evening.
The result is a victory for the PM, by 200 votes to 117. May gets a comfortable majority and, under party rules, is immune to another challenge for a year. Supporters say the leadership question has been put to bed, but critics say the fact that a sizeable number of MPs voted against her is a blow to her authority.
A penny for the thoughts of European leaders watching on. Amid the Westminster turmoil, Brussels makes clear that while it can offer Britain reassurances about the backstop, the withdrawal agreement can't be renegotiated and is the best deal on the table.
The vote on May's Brexit deal is now set for the week beginning 14 January.
Improbably, the PM has made it to Christmas. She - and the rest of Westminster - know that the next few months will likely come to define British politics for years - and most probably decades - to come.
