Irish diplomats have done their best in recent months to maintain perceptions of a discrete remove in the Brexit negotiating process between Irish concerns and those of Spain, notably over Gibraltar.

Gibraltar, I have been told several times, should be seen as qualitatively different, much more of a “post-colonial situation” than Northern Ireland – a perspective that might bear historical discussion.

Spanish prime minister Pedro Sánchez’s last-minute grandstanding threat to the summit last weekend was viewed with some apprehension.

The Irish were not alone in pointing to his domestic political challenges as motivation – local elections this week in Asturias. All politics is local.

But if there was certainly a strong element of local opportunism in Sánchez’s threats, there was also a subtext to the Spanish demands of both the UK and partners in the EU that has echoes of Ireland’s Brexit strategy and of its high, largely fulfilled, expectations of solidarity from partners.

At a meeting of EU27 ambassadors last week, the differences over Gibraltar, and the Spanish demand to be given an explicit veto on future deals involving the colony, reportedly led to a testy exchange with the representatives of one founding EU country.

But Spain’s ambassador, Politico reports, responded vigorously that the issue is “most important” and that “we should not confuse between who is leaving with who is staying”.

Briefing journalists later, one national spokesman recalled that when Madrid had joined the EEC in 1986 it had, like any acceding state, accepted the principle that new members leave old disputes with other members at the door. They are expected to accept and live with the borders inside the union as they find them, albeit without abandoning or repudiating old territorial claims.

Sovereignty dispute

It was quite understandable, he suggested, that a member should see such an obligation ending when the other party to such a territorial/sovereignty dispute leaves the EU.

At that point, the clear implication was the common EU’s perspective on a disputed issue must also change – from disinterested neutral, to a default position of defending its member’s interests.

After the summit on Sunday evening, a senior EU official discussing the meeting with journalists chided one for suggesting the Spanish intervention had in some way been embarrassing or “illegitimate”. No, he said, “all positions of member states are legitimate”.

Many member states have particular concerns which they try to accommodate, he insisted. “The union stands up for its member states – for Spain, for Ireland, for Cyprus – this is the essence of the union . . . You are stronger within.” That he, said was council president Donald Tusk’s very strongly held view .

In truth, in the Brexit talks, Ireland’s position has indeed been privileged at every stage, with Irish officials almost joined at the hip to the negotiating task force. We have been told many times that Irish consent to shifts in negotiating positions is seen as vital at every stage. “Positions evolve together,” the official insisted.

Defending members

A few months ago, I asked Manfred Weber, the leader in the European Parliament of the centre-right European People’s Party, if he could explain the remarkable solidarity that Ireland was experiencing from its partners. He responded like a trade union official: “Ireland is a member, we defend our members.” The UK is no longer one.

Sánchez has responded to the letters of assurance on Gibraltar that he received from those same partners by trumpeting what he claims is a major diplomatic coup.

“With Brexit we all lose, especially the United Kingdom, but when it comes to Gibraltar, Spain wins,” he said on Sunday. He would now demand talks with the UK on joint sovereignty.

“Spain will be a fundamental pillar of the relationship between Gibraltar and the EU as a whole,” he said. “When it comes to the future political declaration, the European Council and the European Commission have backed Spain’s position, and backed it as never before.”

Legally he has certainly oversold his case. The assurances he received, EU and UK officials agree, represent no more than a restatement of the status quo. In trade talks involving the UK and Gibraltar, Spain like every other member state will have an individual veto – nothing changes.

But politically Sánchez may have a point. A subtle shift has just taken place. The EU’s determined neutrality between member states on their territorial ambitions and on preserving its internal borders has just been undermined by Britain’s decision to leave.

After all, the union stands by its members, and “all positions of member states are legitimate”.