The "No 10" Marie Collins incident is a great, entirely true political story.

Marie is married to Michael Collins, Ireland's Ambassador to Germany who was back from his base in Berlin last week when Chancellor Angela Merkel visited Dublin.

Ambassador Michael Collins at a St Patrick's Day parade in Munich in 2018

Marie was a very able nurse at Dublin's St Vincent's hospital when her husband was starting to climb the ladder in his career as a public servant.

In the years after the Good Friday Agreement he had switched from his role in the Department of Foreign Affairs to work in the tight group, led by former Taoiseach Bertie Ahern, that was concentrating on the peace process.

For Michael, frequently it involved long days of difficult discussions in Dublin, Belfast and London.

On one such night Marie was at home in south Dublin, busy dealing with the needs of their energetic sons. The phone rang, distracting her from her task.

"Number Ten…"  said the female voice on the other end of the line.

While Marie wasn't gruff, she was decisive in conveying to the person on the other end of the line that she had dialled the wrong number. (The Collins' house was not number 10.) 

Marie quickly replaced the receiver and got back to her busy life.

The house was calmer when later that night Michael Collins returned after one more extended shift in the office.

He has the discreet ways of a tall man and several minutes had passed before he got around to asking a question.

"Marie, by any chance, was there a call from Downing Street for me?"

If the "No 10 incident" was a case of an unfortunate misunderstanding, Michael, thanks to Marie, got a chance ration of good fortune several years later.

By 2009 he was back full-time in the Department of Foreign Affairs and he was serving in the plum but challenging job of Ireland's Ambassador to the United States, when Barack Obama was elected President.

Ireland Inc. was in a tight spot. For the previous eight years George W Bush had been the occupant of the White House. And for the eight years before that Bill Clinton had been the President.

The Irish network of contacts had worked well during those Republican and Democrat regimes.

But access to the former senator from Illinois and the support staff he had brought with him to the White House might be a challenge for the normally well-connected Irish, Ambassador Collins among them.

It was Marie who made the breakthrough.

One day when out and about in Washington, she met a woman who was familiar from an earlier time when their husbands were on a lower rung of the public office ladder.

Her name is Kathy Pokluda, wife of John Brennan. Kathy explained how John was part of the Obama administration.

John Brennan, the proud son of a Roscommon blacksmith, was appointed Head of Homeland Security by President Obama and would later serve as Director of the CIA. (He is that same John Brennan who crossed swords with President Donald Trump in recent times.)

The chance meeting between Marie and Kathy meant that a friendship between the Collins and Brennan families was rekindled. And the Irish ambassador now had a contact in the White House.

When the new Obama administration wanted to let the Irish government know that the long-standing Bowl of Shamrock presentation would continue in March 2009, the call conveying the good news was made to Michael Collins by John Brennan.

There was something deeper than the immediate about the image of Ambassador Collins, standing off centre, in the photographs involving Taoiseach Leo Varadkar and the Chancellor Merkel in Dublin last week. 

 Berlin is his last posting. He has been there since 2013 and he turns 66 this year.

For him and for a cohort of able, experienced Irish diplomats, this is the iceberg most did not anticipate.

It challenges much of what they have worked on for decades. And it means that at a time when one might be expecting to be tidying loose ends and preparing for retirement, the group is absorbed by an issue for which there are no operating instructions and no obvious solution.

Declan Kelleher who heads up Ireland's EU office in Brussels is a member of this club.

He joined the Department of Foreign Affairs 42 years ago in 1977. Rory Montgomery, Head of the EU Division in Dublin and Barry Robinson, the Political Director who is based in Dublin are two more of a kind.

Some of them joined the Department of Foreign Affairs in the recruitment drive that followed Ireland's admission to the European Union in 1973.

They had flying hours clocked up by the signing of the Anglo Irish Agreement in 1985. They put in busy shifts during the IRA ceasefire (1994) and Good Friday Agreement (1998) phases.

They shared in the relief and satisfaction of the peace process and Northern Ireland's power-sharing years.

And throughout that time, on EU business, in Europe and beyond, some of their most valued and sincere working relationships were with their British counterparts.
Adrian O'Neill, Ireland’s current Ambassador to the UK illustrates the pattern.

He was in charge of the Anglo-Irish division of the Department of Foreign Affairs for significant stretches of the Sinn Féin-DUP courtship.

He was Secretary General to President Mary McAleese during the visit of Queen Elizabeth to Ireland and continued in that role when President Michael D Higgins made his official visit to Britain

His London job is probably his final one before retirement. On his watch advances of the past decade in British-Irish relations are being tested.

Secretary General of the Department of Foreign Affairs Niall Burgess is another who fits the pattern.

An archaeology graduate, he met his future wife Marie at the protests opposing Dublin Corporation's plans to site its offices at Wood Quay.

In the early 1990s he was private secretary to then Tánaiste and Minister for Foreign Affairs, Dick Spring. He availed of time out to work in Brussels under former Spanish foreign minister Javier Solana, the first person to have the Secretary General to the EU Council position, now held by Donald Tusk.

Twelve years ago Niall Burgess was Irish Consul General in New York who welcomed power-sharers Ian Paisley and Martin McGuinness when they rang the bell to open business at the New York Stock Exchange.

They were golden days of the peace process when the British and Irish governments basked in the reflected glory of their shared enterprise and the fruits of their endless patience.

For the most powerful civil servant in the country it is a similar story.

Martin Fraser has been Secretary General to the Government and Secretary General to the Taoiseach since 2011.

While his boss, Leo Varadkar, is a very public Kylie Minogue fan, age is an influence in the fact that Fraser is a Bruce Springsteen aficionado. (His equivalents in the Department of Foreign Affairs might be drawn to the Neil Young-Bob Dylan Kilkenny summer event, Brexit permitting).

Martin Fraser was a senior member of Ahern/Cowen and Enda Kenny kitchen cabinets during different phases of the peace process.

He is on first-name terms with senior Northern Ireland and British politicians and their support staff.

He too finds himself at the centre of a process that jars with the achievements of recent decades. He is one of a group for whom this final turbulent chapter may well define their working lives.

The challenging environment is not confined to Irish minds and hearts.

The current British Ambassador in Ireland, Robin Barnett, arrived in Dublin two months after the Brexit Referendum vote.

For the five years before that he was Britain’s ambassador to Poland and at different stages in his career he served in Vienna and Bucharest.

It's 35 years since former British prime minister Margaret Thatcher made her "Out, Out, Out" comment at a news conference in Downing Street. 

The tension created by Brexit means that Robin Barnett finds himself serving in Dublin when the relationship between the neighbouring islands is buffeted once more, but in a different, new way.
His predecessor, Sir Dominic Chilcott, spent four years during which the Dublin posting was considered a run in the sunny uplands.

He is now Britain's ambassador to Turkey. It is highly likely that he has to write occasional reports to London, on the workings of the EU's customs arrangements with Turkey. 
The British ambassador in Dublin before Dominic Chilcott was Julian King. He had the dream assignment of helping to arrange the State Visit to Ireland by Queen Elizabeth in 2011.  
He witnessed, close-up, the "A Uachtaráin agus a chairde" and the bow in the Garden of Remembrance moments.

And where is Julian King now?

In September 2016, three months after the UK’s Brexit vote, he took up the role of British member of the European Commission.

The diplomat who accompanied his monarch on her historic visit to Ireland is on course to be the last British official to hold a position and a portfolio in the European Commission.

You may be measured by how you deal with the unlikely is advice sometimes given to young diplomats.

But was there ever an unlikely like this?