The Brexit negotiations, which started this week, will be the ghost at the feast of the two-day European Union summit that opens today in Brussels: ever-present, looming over all the decisions, but not officially on the agenda.
They will be the main theme, however, of the series of bilateral meetings with his fellow leaders that Taoiseach Leo Varadkar, attending his first summit, will be having. He has already spoken to the new French president, Emmanuel Macron, and to Germany's chancellor, Angela Merkel, and has met the British prime minister, Theresa May.
Varadkar will meet the European Council president, Donald Tusk, at Thursday morning's meeting of the leaders of the centrist European People's Party, and officials expect him to have a series of other encounters on the fringes of the summit.
At the dinner on Thursday Theresa May will get her only chance to present an assessment of where the talks may be heading in the wake of the UK election
At the dinner on Thursday evening, after discussions of the leaders' recent encounters with the presidents of the United States, Donald Trump, and Turkey, Recep Tayyip Erdogan – which may not do much for their digestion – May will get her only chance to present an assessment of where the talks may be heading in the wake of the British general election.
She is expected to use the opportunity to outline for the first time the United Kingdom’s position on the rights of UK and EU citizens residing in each others’ territories after Brexit. The issue is one of the three priority discussions for the Brexit negotiations in the preliminary “divorce” talks.
After dinner, perhaps as a pousse-café, the 27 other leaders will meet without May to discuss a contentious but now agreed methodology for deciding where the plum prizes of the UK-based EU institutions will be relocated. Ireland has a particular interest in the European Medicines Agency, but there is fierce competition for that and for the European Banking Authority.
Brussels rumours, fiercely denied, suggest that the French and Germans have already carved out a deal for them, but some 20 bids are expected for the two agencies, and an elaborate mechanism has been devised to decide where they will go.
In the end, this autumn, each member state will get one vote on each agency – but only after the European Commission has "objectively assessed" the merits of each proposed new home in terms of infrastructure and other capacities. The eastern Europeans have lobbied, apparently unsuccessfully, for "objective criteria" such as geographical spread and "value for money" (an ability to pay lower wages) to be included.
An Irish official insists that “we have nothing to fear from an objective assessment”.
The real meat of the summit will be discussions about enhancing defence co-operation in the face of terrorism and a debate on jobs and growth that will focus on trade issues
The real meat of the summit, however, will be important discussions about enhancing defence co-operation in the face of terrorism and external threats, and a debate on jobs and growth that will focus on trade issues.
The leaders will agree on "the need to launch ambitious and inclusive permanent structured co-operation" on defence, putting flesh on treaty provisions that allow for the union, or subgroups of it, to organise a range of military tasks together – anything from enforcing peace to sharing weapons research.
Ireland has been among the states to emphasise “inclusivity”, making clear that it sees itself as a likely part of any group of willing states and that it does not want to see the emergence of two-speed defence co-operation. If two speeds emerge we want to be with the advance guard.
There will be strong encouragement to justice ministers to step up co-operation and information sharing over foreign fighters and those returning from Syria.
Although the EU leaders will certainly endorse a strong declaration in favour of trade and condemning protectionism, they will come under pressure – likely to be unsuccessful – from some states to strengthen their "trade defence instruments" to allow states to prevent what some, including the Germans and French, see as dangerous takeovers by Chinese business of strategic businesses in Europe.