A door opens as barriers are removed 

From the outset, the four parties negotiating the treaty were clear it was about people. 

Brexit, which only a handful of us voted for, had left Gibraltar in the lurch. In the process, it had dropped the Campo in it too, La Linea in particular. 

Much as it might rankle with some people on both sides of the border, there is an inter-dependency that cannot be denied, or ignored. Brexit threatened to rupture it. 

Last night at midnight, the frontier controls so often used in the past as a political weapon by Spain were removed. 

And people answered, on both sides. And while a crowd this size is hardly representative of views across two communities, the absence of hostility and spontaneous mingling were striking. 

There were large crowds on both sides but no one was really counting, at least officially. We estimated it was around 2,000. It might have been more, it might have been less. But it was enough to send a clear signal. 

On the Gibraltar side was a large gathering of interested onlookers there for the historic moment, mingling with people who just moments earlier had attended a reception hosted by Chief Minister Fabian Picardo. 

On the Spanish side, a large and boisterous crowd waving Spanish flags, fresh from watching Spain beat France 2-0 to secure a place in the World Cup final. 

I was in the middle of it all as both sides surged forward and for a moment I thought there were going to be problems. I was wrong. 

It turned into a celebration and the word I heard most was “surreal”.  

Among the many people I spoke to was a man from La Linea called Juan Sanchez Cerdoñez. His father had worked in Gibraltar and at the age of 70, after 50 years in Madrid, Mr Sanchez had bought a house in La Linea and moved back. 

He broke down in tears as we spoke, overcome with emotion. Through sobs, he said the scenes around us made him happy. 

“We’ve always got on well,” he said. “Gibraltar put food on our table.” 

Two steps away, I spoke to Kyle, a 22-year-old Gibraltarian who was there with his girlfriend and other members of his family. 

“I think this is the future,” he said. “It's the way forward. We got to move on.” 

Between them was a glimpse of what this treaty is about, the door it has opened for young and old alike on both sides of the border, some happy the bitter wounds of the past may finally start to heal, others looking at a world of opportunity ahead. 

At a time when so many countries are looking inwards, building barriers and resolving problems through conflict, Gibraltar, Spain, the UK and the EU are pulling down a border, literally.  

Who would have thought it possible 10 years ago on the morning of June 23, 2016, when we all woke up to the news that we were being dragged out of Europe? It’s a legal document, but there’s some poetry in those pages. 

Now make no mistake about it, not everyone is happy with this deal, and that’s fair enough.  

There are many in Gibraltar who remain concerned about security, for example, worried about a surge in crime, and these are legitimate fears after years living in a gated community of sorts. 

But we are repeatedly reassured that high-tech surveillance and beefed-up law enforcement resources will make Gibraltar safer than before.  

One can take or leave that assurance, but let’s also remember that the old fence was porous and had more holes in it than a Swiss cheese, and that we too have our fair share of homegrown unsavoury types of all sorts. Just look at recent court reports. 

There are people who don’t like it in Spain too, who feel too much has been given away and not enough gained. Others say it’s a missed opportunity to advance Spain’s sovereignty claim when Brexit had placed Gibraltar on the back foot.  “Gibraltar español”, that phrase that harks back to a dictatorship, remains a default knee-jerk reaction whenever Gibraltar is mentioned, sometimes voiced with far more reflex than conviction. 

Others of the Vox school of thought, however, take it far more seriously than we would want, and that cannot be ignored going forward. 

Implementation will be a challenge, dependent in large part on continued goodwill that may dissipate in future with political change. 

The treaty is with the EU, not Spain, but its implementation will depend largely on how Madrid approaches it, and that in turn will depend on what flavour government is sitting in Moncloa. 

Don’t underestimate either the technical challenges. Last night, work was still under way setting up the EES system in Sir Joshua Hassan Gibraltar International Airport ahead of the arrival at 10am today of the first flight under the treaty framework, another three scheduled over the rest of the day. 

If there are problems with the e-gates, we may start to hear about them today. But then the EES isn’t working very well elsewhere in Europe, so we’re far from special in that respect. 

Inevitably though, if stuff can go wrong in the coming weeks and months, it will. We should be ready for that. As one senior official put yesterday, “we’re now in the teething phase”. 

And yet yesterday in Brussels, when I asked both Mr Picardo and Spanish Foreign Minister Jose Manuel Albares how challenging implementation would be, they both shrugged off the question with similar answers. 

The negotiation had been tough and the arguments had already been had and resolved, the solutions set out in fine detail in a treaty that runs to over 1000 pages, without including scores more pages in annexes and operational agreements that we will pick over in coming days. 

We will see how all of this works in practice. 

Dr Joseph Garcia, the Deputy Chief Minister, who tends to steer clear of the limelight but has played a central role in negotiating this deal, shared another thought with me. 

He said last night amounted to “dismantling the architecture of restrictions” and the weapon Spain had used against Gibraltar for so many decades. 

I put it to him that the weapon was surely now at the airport. 

“It's different because those are European controls,” he told me.  

“They are in a treaty environment very closely monitored and regulated.” 

“There's an appeals mechanism in the treaty, a dispute resolution mechanism.” 

“So I think we are far more safeguarded and far more protected than we have ever been.” 

It reminded me for a moment of being in the EU, go figure. 

At the border yesterday, I asked La Linea mayor Juan Franco about implementation and he complained that, on the Spanish side, questions to various ministries in Madrid about how they will deal with practical matters had, so far, gone unanswered. 

He said it was vital there was cross-border coordination and that all frontline stakeholders, him included, were properly heard. 

“But let’s leave that for another day,” he implored. 

“Tonight is about celebration.” 

And he wasn’t just talking about football.