On 24 June 2016, the day after Britain voted to leave the European Union, Jean-Claude Juncker, Donald Tusk and Martin Schulz issued the EU’s first formal response to a decision they described in a joint statement as “regrettable”, but said they respected.

The bloc stood united, the presidents of the European commission, council and parliament said. Defence of its stability and interests was its priority, so any Brexit agreement with the UK would be “balanced … in terms of rights and obligations”.

In the days that followed, Angela Merkel, the German chancellor, and François Hollande, then France’s president, put meat on the bones of that anodyne little phrase. “There can be,” Merkel told the Bundestag – adopting a term destined to become famous – “no cherry-picking.” There must, she stressed, be “a palpable difference between countries who are members of the European family, and those who are not.”

Hollande was even plainer: an “à la carte” EU was not on the menu, he said. Being in the single market “has advantages. The UK must face the consequences of its decision”.

Two-and-a-half years on, the withdrawal agreement and political declaration are all but complete, and the first phase of the process is finally over – at least for the EU27.

A lot on the continent has changed since. Regret remains, but a page has turned.

Schulz has sunk without trace in Germany; Hollande is no longer president of France; Merkel will not stand again. Populist, far-right and Eurosceptic parties have risen (or returned) to power in Italy, Austria and Hungary and made record gains in Sweden.

However, in a famously fractious bloc which is often unable to agree on anything much, the common understanding on Brexit reached, very rapidly, by 27 different capitals in early summer 2016 has not just survived but intensified into an unlikely unity of purpose that, ultimately, made the divorce talks’ outcome inevitable.

Each individual EU member state may be facing different consequences and costs from Brexit, and each – as well as the bloc’s central institutions – necessarily has a different experience of the talks. But ask for their top Brexit takeaway so far, and the most common response is: EU solidarity matters, and it works.

That, and some surprise at the UK’s ineptitude. “It was clear to most Europeans that the Brexiters’ promises were empty,” said Anna-Lena Högenauer of Luxembourg’s Institute of Political Sciences. “Most, though, thought it was just politics, that there was some kind of plan behind the rhetoric.”

The discovery that there was not, Högenauer said, was something of a shock. “The UK basically jumped into the ocean blindfold, and started paddling round in circles. It was almost like it expected the EU not just to say what Brexit should look like, but to devise a version of it that would suit Britain.”

View photos Angela Merkel set out the position of the EU27. Photograph: Marquardt Christian/Rex/Shutterstock More

Europe’s unity was far from a given at the outset, said Fabian Zuleeg of the European Policy Centre, a leading Brussels thinktank. “There was real regret, of course, but also huge uncertainty, in the immediate aftermath of the referendum,” Zuleeg said. “Real concern, if not fear, of what might come next, and of how the process might unfold.

“But it led to a quite remarkable coming together of the EU. The key red lines, and the sequencing, were set very early.”

The EU, uncharacteristically, was moving purposefully on. “It was an existential moment,” said Salvador Llaudes, of the Universidad Autónoma of Madrid. “A moment of truth. There was an understanding that a partner was leaving – not just any partner – and that how the EU responded would decide its future.”

The foundations of Michel Barnier’s mandate as the European Union’s chief negotiator – no negotiation before article 50; no cherry-picking benefits of the single market without accepting all its obligations; no trade talks before Brexit – were laid at an EU summit held less than a week after the referendum. And they have not budged significantly since.

Story continues