Perhaps the greatest turning point for Parliamentary involvement in the Brexit process was the 2017 general election. Having won an unlikely majority in 2015, Cameron bequeathed to May a relatively functional dynamic in Parliament. But, tempted by artificial sentiment in polling, May and her team decided to call the 2017 election in an attempt to secure a greater popular mandate for her administration. That decision was fatal. The prior polling was erroneous, or at the very least misread the public appetite for an election, and the campaign May ran was self-defeating. The loss of the Conservative majority at the election left May in the treacherous position of needing a confidence and supply deal with the Northern Irish Democratic Unionist Party (DUP). Even in normal times, the instability of such an arrangement creates complications and often disaster for the ruling party. When you add in the unique circumstances of Brexit, plus the fact that the Northern Irish questions in Brexit were the most difficult and contentious elements of the negotiations, May’s dependence on the DUP was fatal.

It was supposed to be a relaxing holiday, a week away cruising the Adriatic in a chartered yacht as the guest of a friend with far deeper pockets, and thus a lifestyle more sumptuous than I had ever experienced. There were just ten of us aboard, some meeting for the first time but, as one day slid into the next under the hot June sun, we started to bond, confide and laugh over the wine-fuelled meals stretching over hours. And so it was that one lunchtime, as the conversation was providing nothing more than a soft and sociable soundtrack to the stunning Croatian coastline, suddenly everything changed. Brexit came up.

Painful as it is for a Remain campaigner like me to admit, the EU has always been dire when it comes to policies for supporting innovation and technology. Even more painfully, things have worsened over the past ten years. Longstanding structural weaknesses in EU innovation policy date from well before the Brexit referendum in 2016. The European Union had dismally failed to create a regulatory environment conducive to technological innovation. As I found whenever I visited to Brussels as a No. 10 adviser under David Cameron, the policy instincts of European Commission officials were overwhelmingly rooted in market stability and risk avoidance – values that, while defensible in themselves, often produced unintended consequences for fast-moving sectors such as digital technology and life sciences. Take the EU’s data privacy rules, which were debated and developed for years before being finally implemented in 2018. As Cameron’s team repeatedly warned at the time, the compliance costs fell disproportionately on small and early-stage firms. Even before fines or litigation, the administrative burden for smaller organisations typically ran into tens of thousands of pounds.

‘The price of victory’ was how Jean Monnet, pioneer of European integration, described Britain’s self-exclusion from the foundational years of European integration. As a late entrant (1973), it was obliged to accept many arrangements that did not suit its interests. Margaret Thatcher and her successors tried to negotiate opt-outs to protect what they deemed Britain’s vital interests as the European Community developed into the European Union (EU), until David Cameron tried to resolve the issue once and for all through renegotiation and an in-or-out referendum. Cameron was outwitted by Boris Johnson – a brilliant political showman – but he in turn had no strategy for his surprise Brexit victory. The chapter explores the struggles of successive Tory premiers – especially May, Johnson and Sunak – to hold their party together and get Brexit done, without isolating Northern Ireland from the rest of the UK. After the Tories lost the 2024 election, the new Labour government was left on the sidelines of the EU, trying to sort out piecemeal opt-ins – an ironic inversion of Britain’s posture when it was inside the EU.

Sterling depreciated by around 10 per cent on a trade-weighted basis immediately after the vote, raising prices faced by consumers by an estimated 2.9 per cent in the two years after, with a consequent effect on reducing real living standards. For firms, the referendum and its aftermath of political instability increased uncertainty and raised barriers to investment. We focus mostly on the longer-term consequences. We start by outlining, briefly, the key economic claims and forecasts made at the time of the referendum. These matter not just for historical purposes but because ‘consensus’ estimates and assumptions made by key policymakers, notably at the Office for Budget Responsibility, have changed little since then. We then present some of the basic data on UK economic performance over the period and draw comparisons with similar countries. We then consider in more detail what has happened to trade and business investment, the key routes through which any economic impacts are likely to have been transmitted. We briefly review claims that big regulatory changes might have had positive effects.

Leaving the EU marks a generational shift in the way the country is governed, but it is not an end in itself. It is an opportunity to do things differently – economically, politically, on the world stage. Whether we grasp that opportunity is up to us. Leaving was never going to bring an immediate boost in prosperity – on the contrary, some contraction in the short-term was inevitable, as the country and business adjusted. The impact of external events like Covid and the Russian invasion of Ukraine provide some mitigation. But outside the EU, so far, we have taken only small steps. I fear we are still in our silos, wedded to outdated thinking, resentful and too timid to make the changes we need. The jeopardy our continent faces demands an urgent response. This means actively working to put differences aside. It means finding the imagination to design a joint future. A more durable alliance with our continental neighbours, is an imperative. Without it, we – and they – face continued decline and dangerous dependence on more powerful nations.

The promise to end free movement of EU citizens was a trump card for the campaign to leave the European Union. Unlike the economic and sovereignty arguments, the immigration argument was simple and undeniably true: the UK could not control immigration while it remained a member of the EU. Experts on both sides of the referendum debate agreed that leaving the EU would reduce migration. For many voters, that was a pretty compelling argument. Fast forward six years, and migration post-Brexit had hit a record high. Net migration was three times the pre-Brexit level. What happened? Why did EU exit fail so spectacularly to deliver on its clearest promise? This chapter argues that the post-Brexit immigration system broke its promise to reduce migration partly by accident and partly by design. The government made liberal choices on immigration policy and underestimated quite how many migrants would take them up. Hardly any of this was an inevitable consequence of Brexit. In an alternative universe, things could have looked very different.

Britain’s decision to leave the European Union was perhaps the most divisive and consequential event of modern British politics. To assess its impact on the tenth anniversary of the referendum, Anthony Seldon assembles an unparalleled list of writers from all sides of the debate – including Brexit MP Steve Baker, ex-Cabinet Secretary Simon Case, election guru John Curtice, economist Paul Johnson, ex-Foreign Secretary David Miliband, ex-Cabinet minister Emily Thornberry, leading lawyers Marina Wheeler and Jonathan Sumption and ex-Archbishop of Canterbury Rowan Williams. They analyse why the referendum happened, how Brexit became law and its impact on every corner of British life, concluding with a range of perspectives on how Britain might make the most of the opportunities now available to it. As the dust continues to settle, The Brexit Effect delivers a vital and timely analysis for all who wish to understand Britain’s past, present and future.

When the Brexit referendum result came in, Tony Gallagher, editor of the Daily Telegraph, triumphantly texted the Guardian newsroom: ‘Who said the mainstream media was finished?’ Gallagher was apeing Kelvin McKenzie, one of his predecessors as Sun editor, who proclaimed after John Major’s upset election victory in 1992: ‘It was the Sun wot won it!’ Brexit appeared to vindicate his view that the press, in particular the Sun, had tipped the balance in favour of Leave. The mood inside the FT newsroom was funereal. Over at The Sunday Times, Michael Sheridan, a veteran foreign correspondent, arrived early that morning to see Martin Ivens alone in the editor’s office. ‘What have you done?,’ he exclaimed, extending a congratulatory hand. Ivens held out the possibility of a renegotiation based on the Brexit vote followed by a second referendum.

Only one person can answer as to the sincerity of the decision Boris made to back leave. The now infamous two articles allow his enemies to present his decision as an act of calculating duplicity for which they will forever believe him guilty. This perhaps also provides a focus for the real cause of their angst – that he beat them. I can only observe that I saw him use this device often in decision-making. Whatever motivated his decision in February 2016, he certainly owned it from there on. Johnson’s arrival as the public face of leave brought energy and stardust to the campaign. New voters seemed to ‘have permission’ to vote leave because of Johnson’s arrival. He moved the centre of gravity of the campaign away from the purely Faragist proposition. A good test of the effectiveness of the message was in the reaction of some of the arch-Brexiteers. Supreme bores like Bernard Jenkin deeply resented Johnson, whom they regarded as a Johnny-come-lately. Those not stuck in the time warp of 1992–7 rejoiced at it.

Our SW1 insurgency was bolstered by the People’s Pledge, a cross-party campaign for a referendum, launched in 2011 by Daniel Hodson, John Mills, Mark Seddon, Dan Hannan, myself and others. It effectively pressured MPs in marginal seats by organising local referendums, pushing them to support a national vote. I saw its impact firsthand at a drinks party in David Cameron’s Downing Street flat, where an irate MP confronted me about the campaign’s activity in her constituency. My suggestion that she sign the pledge sparked a scene. (Ironically, this now-former MP later framed her parliamentary legacy as helping secure Brexit, another case of selective memory.) In a move that would prove significant in the long run, Boris Johnson, then the London Mayor, had signed the People’s Pledge at one of our street stalls in Romford. We had not only mainstreamed the idea of a referendum, but had been able to do so because we had taken control of the Eurosceptic movement inside Westminster. Once Cameron had conceded holding a referendum, it was what was happening with Euroscepticism outside Westminster that became of greater concern.

‘He thinks you’ve completely fucked yourselves.’ This was Washington DC in late June 2016, a couple of days after the Leave victory, lunch with one of Obama’s inner circle, and his response to my question about how the President had viewed the outcome. My guest continued, ‘We just don’t understand why you would call a referendum which you didn’t need to hold without being absolutely certain of getting the right answer. Why would you do that? And what happens now you’ve blown yourselves up?’ The Obama team had form in questioning David Cameron’s judgement. They blamed him for miscalculating UK Parliamentary opinion on a proposed US–UK–France attack on Syria, summoning Parliament back from holiday in August 2013, then losing the vote, and triggering a chronically cautious Obama to back away from his plan to bomb Assad’s military bases. Brexit, in their eyes, was more of the same. But the mood on the nightly Washington social circuit was similar: I noticed people staring at me with a near-horrified look in their eyes: ‘What have you done?’

All we had to operate on was gut feeling. My gut feeling was that we were in deep trouble, and that the confidence, indeed the arrogance, of the Remain campaign was being fuelled by a failure to speak to enough voters outside London and the other big cities. I spent the day of the referendum in my constituency getting out the vote. On Upper Street, every single person was wearing an ‘I’m in’ sticker. I spotted the one and only man who wasn’t and offered him one. He said that he was happy to wear it in London, but would be taking it off when he went home to Peterborough. Again, I saw that you could be caught up in the bubble in London and assume everything would be fine, but the moment you stepped out you could see that it wasn’t. I went into that evening with a really heavy heart. I was sent out on the media round, to a massive great barn in outer London from which the BBC was hosting its referendum coverage. I was waiting in the wings at 4:40am when David Dimbleby announced ‘We’re out.’

We were on opposite sides of the Brexit divide, perhaps the most divisive issue since 1945. Steve publicly campaigned hard to end the jurisdiction of EU law and institutions in the UK. Paul voted Remain but was much less concerned about the issues. Steve is sometimes lauded, but still widely hated for his efforts. Many of Paul’s colleagues were shocked that he didn’t care very much about an issue they saw as existential. We met on Zoom during Covid, when we shared similar concerns about the harms of lockdowns. The libertarian MP and the leftie academic didn’t expect the call to last very long. But we agreed on much more than we expected to – and we liked one another. We wrote against ‘vaccine passports’ in The Times. Paul was astonished by comments on the article, which were overwhelmingly about Steve’s work on Brexit, which had nothing to do with vaccine passports. Paul was attacked by several colleagues not only for disagreeing with lockdowns, but also for collaborating with a horrible Brexiteer.

The biggest problem that the vote threw up was precisely the lack of clarity about what would come next; what unexpected surprises were to come next? What would the UK’s departure mean for Britain and for the European Union; what, indeed, would it mean for countries in other parts of the world? Would Brexit start a domino effect in Europe; might it even start a chain reaction elsewhere too, as countries stepped back from international commitments and out of regional or global institutions – and turned their backs on former partners and allies? In the days after the vote, press commentaries around the world began to harden. On 24 June 2016, for example, the Chinese Ministry of Foreign Affairs noted that it respected the results and hoped for early agreements between London and Brussels to help clear up uncertainty. Three weeks later, voices in Beijing had a better grasp on what had happened – and in particular realised that the promises given by Brexit’s chief cheerleaders were hopelessly naïve at best and downright dissimulations at worst.

The author tracks his political journey from being a sceptical Remainer in 2016 to a persuaded Brexiteer in 2026. On economics, he accepts that Brexit has damaged Britain’s trade in goods and rate of economic growth in the short term – although not nearly as much as Remainer fearmongers prophesied. Yet, he reckons that loss will be more than compensated for in the long term by Brexit-freedoms to make trade agreements that open the likes of India up to British services, and to exploit artificial intelligence’s technological potential within a lighter, more flexible regulatory regime. However, the main reasons for the author’s conversion are constitutional. Brexit restores sovereignty to the British government, empowering it to address politically destabilising issues such as the control of the rate of immigration. It will allow Britain to withdraw from the European Convention of Human Rights, which is necessary to retrieve legislative power from unelected courts and restore it to Parliament. It renders Scottish independence even more economically irrational than it already is. And it thereby helps to make less likely the disintegration of the United Kingdom, which would weaken the West at a time when it needs to keep all its pillars standing strong.