The word “historic” is overused in politics, but today truly merits the title. At 12.30pm, Sir Tim Barrow will deliver a letter from Theresa May to Donald Tusk, the President of the European Council.

In those pages, the Prime Minister will use the power vested in her by Act of Parliament to inform the European Union that the United Kingdom is triggering Article 50, and wishes to leave the organisation. The two-year process of negotiating Brexit will begin.

So begins the last act of our nation’s turbulent membership of the Eurofederalist project.

What was pitched as a Common Market but became a nascent superstate has split a faultline through British politics since the 1970s – the EU debate generated noisy campaigning, quiet deliberation, divisions between parties and divisions within parties, the fall of two Prime Ministers and the fatal emasculation of a third. It brought us close to losing our currency, impinged heavily on our sovereign right to democratically govern ourselves, drove millions of voters to disillusionment and split first Labour and then the Conservatives. From Margaret Thatcher’s flag jumper to her speech in Bruges, and from John Major’s excoriation of the Maastricht “bastards” to Nigel Farage’s insurgency wearing “fruitcakes and loonies” as a badge of pride, it has the unusual distinction of being an incredibly dry and technical topic on paper which evokes almost unparalleled passions in practice.

It was a Conservative government, under Edward Heath, which took us into what became the EU, and it is a Conservative government, under May, that will now take us out again. This is an outcome which ConservativeHome has supported for many years, and which I have supported for even longer than that. For those – of all parties and none – who campaigned to leave the EU during the dark days in which it was dismissed as a fringe interest, today begins the process of making those innumerable years of work worthwhile. Pounding the pavements, gathering in small meeting places above tired pubs, sticking at it when all seemed lost, and, yes, “banging on about Europe” took determination and belief from many people. Few of them ever expected any recognition for their work, and even fewer ever received it.

They deserve a moment of congratulation. Not just because they won, but because they have demonstrated that our democracy and society is still true to the principles of which we like to boast. People can change the course of history. Ordinary people can make the powerful do what they demand if they gather enough support. Persuading others can produce fundamental change peacefully. Democracy is real, not a theory, a mirage or a confidence trick.

Two other groups deserve our thoughts today.

The first are those who voted Remain. As I wrote on 26th June last year, many of them feel an understandable grief at their defeat on something about which they care very deeply. For some, that experience of defeat will be made more, not less, stinging by its rarity in their lives. We should appreciate the reality of that feeling, recognise its power, and pay credit to the many, many former Remainers who have struggled to do what a democratic society demands: to accept and adjust and move on after an outcome you did not want. The shrinking minority who still hope that the referendum outcome can be ignored must be disagreed with, and must not get their way, but their former allies deserve our appreciation for not following them down the unhealthy route of denial.

The second group are those who voted Leave. The 17,410,742 people who, together, formed the largest vote for any idea, person or party in British democratic history. They were assailed from every commanding height by dire warnings, and often derided both harshly and unfairly, but they thought the issues through for themselves and stuck to what they believed was right.

Among them were an estimated 2.8 million people who normally do not vote, but recognised the importance of the moment and broke the habits of many years. They had given up faith in voting as a way to change things, but they gave it one more go. Today, many people who had thought themselves powerless will be watching as the most powerful people in the land begin do as they asked. The power of that moment to convince such people that democracy does work and that their vote does matter should not be underestimated, the opportunity must be taken to keep them engaged, and the responsibility to honour that instruction must not be denied.

This is not the end of the process. Even leaving aside those trying to wish the referendum result away, there are many more fervent debates and hard decisions yet to come. The job of unpicking the uneasy grafting of EU law into British law will be vast and complex, as will the negotiations on our future relationship, both of which are about to begin. People will disagree, as is their right and responsibility, probably many times; referendum-time alliances will break; new relationships will form, and fall again; and the wheels of our politics will turn on, eating up problems and churning out answers.

That, in itself, is an already visible benefit of Brexit. Our Parliament, and our wider democracy, has begun to flush with new life even before we finally escape the EU. The Article 50 Bill – just 137 lean words – had Parliamentarians energetically pitching clashing cases about fundamental principle at one another. Even more rarely, many voters followed the Westminster back-and-forth in detail.

As we settle on our terms of exit, and then decide what our country will look like after it leaves, voters and politicians alike will regain true control of all the essential laws of our nation for the first time in 45 years. At each election from then on, we will democratically set the policies that affect every aspect of our lives and which will shape our nation’s future. This is just the beginning.