'W hat's the postcode for Kensington Palace?" quipped Taoiseach Leo Varadkar to Prince William and Kate Middleton in the confines of his office.
Mr Varadkar was translating the requirements of the official visitors' book from Irish to English for the Duke and Duchess of Cambridge.
William, already an aficionado of dad jokes, had seemingly met his match in our nation's leader. On arriving at Mr Varadkar's office, William similarly joked to nearby staff members waiting for a glimpse of the royal couple in an adjacent room, "You look very busy!", met with bursts of laughter.
After the obligatory posing for cameras, the Cambridges, along with Mr Varadkar and his partner Matt Barrett, took their seats underneath a portrait of Michael Collins to discuss the business at hand.
"We first met at the 2012 London Olympics," the Taoiseach could be heard telling William as press were ushered out so the foursome could speak in private.
Both parties hit it off so much that the Cambridges went over their allotted time, spending 25 minutes in deep conversation with Mr Varadkar and Mr Barrett for their private tête-à-tête at Government Buildings.
Stability, compatibility and charm are the non-negotiable goals of this visit, Kate and William's first to this country over the course of their nine-year marriage.
With the uncertain aftermath of Brexit looming, the Cambridges were sent as agents of soft diplomacy to copperfasten positive Anglo-Irish relations.
Both Kate and William seemed acutely aware of what was at stake and stayed in deep conversation for as long as possible at all engagements to ensure all the waiting press got the shot they needed from a variety of angles. And, essentially, that their hosts were satisfied.
It was a notable departure from the chaotic energy of William's brother Harry and Meghan Markle's visit in 2018.
The entire day was unfailingly wholesome, bolstering their reputation as down-to-earth parents.
Kate shone in particular, engaging in conversation with President Michael D Higgins about acorns and shrubbery on the grounds of Áras an Uachtaráin, after enjoying a tea party in the drawing room with the Higginses and ambassadorial representatives from Ireland and the UK.
Their afternoon tea menu comprising shamrock shortbread, oat biscuits and lemon drizzle cake, made by the Áras's resident chef, was a fanciful take on an otherwise formal affair. In the same vein, Barry's Tea was served in bone-china sets.
Throughout a day of diplomatic engagements, Kate was dressed in a green silk patterned Alessandra Rich dress and Catherine Walker coat.
She seemed to take particular delight in ringing the Peace Bell, which is suspended between two oak trunks in the grounds of the Áras - one from Co Antrim and the other from south Dublin - in honour of the Good Friday Agreement.
It was a sensible start to the visit as the Cambridges are believed to be staying at nearby Farmleigh, the State guest house that has hosted nearly every visiting dignitary including Britain's Queen Elizabeth and Prince Charles, and Canadian Premier Justin Trudeau.
But this trip is as much about reconciliation as it is fashion analysis, cheesy jokes and an undoubted marketing coup in the ongoing Barry's vs Lyons debate.
The couple laid a wreath at the Garden of Remembrance in Parnell Square, built to honour those who fought for Ireland's freedom.
As second in line to the British throne and queen-consort-in-waiting, it was the most historically significant moment of their trip, following in the footsteps of Queen Elizabeth and Prince Charles before them.
But last night was a more informal affair as the royal couple visited the Guinness Storehouse - where they sipped on the obligatory pint of plain.
William told guests at the event, who included Ireland rugby player Garry Ringrose and actors Liam Cunningham and Robert Sheehan, how his grandmother was "shown how to pour the perfect pint here in 2011".
"Ladies and gentlemen, let me tell you it is not often that I find myself following the queen to the pub," he joked.
"But I am looking forward to testing for myself the theory that Guinness tastes even better in Ireland than overseas," he added.
Day one of their visit showcased the diplomatic talents they have spent nearly a decade perfecting, including subtle nods of normality that have made them so likeable.
When entering the State Reception Room for a photocall that seemed to go on awkwardly long, even Kate shrugged in an endearing laugh.
Ms Higgins had also been captivated by her charms, holding her hand tightly as they walked down the stairs of the South Portico.
The foursome were in constant laughter as they walked through the gardens.
The Higginses had their own secret weapon up their sleeve in the form of their Bernese mountain dogs, the 'first dogs' who have become a fixture on State visits.
Bród jumped to greet the guests with glee, while Síoda is recovering from paw surgery so didn't make it to the photocall.
It's hard not to be charmed by Kate's genuine nature, a country girl turned future queen.
With 13 total engagements over the next 48 hours, including travel around coastal Dublin, Kildare, Meath and Galway, their itinerary was designed with the most impact in mind - and if day one is anything to go by, this might be one for the books.