EU ambassadors in Ireland have warned their capitals “the Irish border question needs to be answered” in the Brexit talks and speculate on the prospects of a united Ireland.

The private message comes in an internal, 4,000-word joint analysis to their capitals of the state of Ireland, circulated ahead of the pope’s visit to “a completely changed Irish society”. It is written by six envoys of the EU’s founding states and has apparently been seen by a wider layer of diplomatic contacts.

It is an opportunity, the note says, “to look back and try to understand” the reshaping of “the open, dynamic, cosmopolitan Ireland we know today”.

The ambassadors warn the Northern Ireland peace is “still is a volatile peace, though, and fears of a re-emergence of conflict due to Brexit are palpable in almost all conversations in Ireland.

“With Brexit, old ghosts from the past come back to haunt the Irish island and questions that no longer deemed relevant have come back to the forefront again. This is illustrated in particular by the border question.”

They warn that “the future of Northern-Ireland and its relation with Ireland strongly depends on the final Brexit deal. . . . With the ongoing negotiations, people are less inclined to say that a united Ireland will not happen in their lifetime.

“A bad deal for Northern-Ireland can speed up the process towards a possibly united Ireland. With a bad deal the North can lose both of its most important revenue streams, the all-Island economy and UK as well as EU subsidies.

“Plus, by 2021 demographics indicate a decisive change: the majority in NI will then be of Catholic faith. This could trigger people to rethink and change their opinion on the possibility of a united Ireland. Crucial questions would have to be answered: How to accommodate those who feel British? How to incorporate the many differences (as a most recent example: different abortion laws).

“And: any reunification would be financially extremely costly for the Irish State. Sensible, transparent and accountable decisions are vital for Northern-Ireland and the country as a whole, because of the delicate balance regarding the Northern-Irish peace project.”

The note looks at social and economic changes in the Republic since the last papal visit, not least the declining authority of the Catholic Church, which “has created a social gap in society and currently we are still seeing both the State and its people looking to find a new balance in social structures now this very important pillar in life is becoming still less influential”.

But Irish citizens “have started to think for themselves and had other options than dependence on faith”.

And the note asks whether the sustained growth in the economy can last - “Ireland the Celtic Phoenix or merely a case of Leprechaun Economics?”

“The country has many important decisions to make in the near future that will shape the society for the decades to come,” the report says.

“To name a few: deciding on the next step of Europeanisation and a changing relationship with the UK because of Brexit, becoming less dependent of foreign direct investment and large multinationals from the United States, reforming its health-system to bring it on par with Western European standards, re-energising the improvement of education as well as structural changes to the role of the church in education, dealing with the current ‘rich-man’s problems’ of overly expensive residential space - which has been called a true housing crisis - and investing in the infrastructure needed to accommodate economic and population growth.”

The note is signed by the six ambassadors of Belgium, France, Germany, Italy, Luxembourg, and the Netherlands - respectively Pierre Emmanuel De Bauw, Stéphane Crouzat, Deike Potzel, Paolo Serpi, Jean Olinger, and Peter Kok.

Full text of the analysis is here.