The Queen is to visit Ireland for the first time on 17th May.
She's visited nearly every country on the globe, yet never her nearest neighbour.
Even 5 years ago the suggestion of a state visit to Ireland was politically impossible.
But the Celtic Tiger brought a new confidence and for the first time Ireland was ready for a meeting as equal allies, rather than as a former colony.
What's fascinating is that up at the level of politics and official ideology, there's always been a nexus of misunderstandings and anxieties about the Anglo Irish relationship.
Talk of a state visit provoked one Irish newspaper to say it 'ought to be a matter for mild curiosity or benign indifference.
And yet, even now, it touches one of those twitchy, tender nerves that remain inert most of the time'.
But down at the level of real life as it is lived, no two peoples on the face of the planet are closer.
Writer and broadcaster Joseph O Connor knows this first hand.
'The book that reveals most about the relationship between Ireland and England is no novel or history textbook or learned tome, but the telephone directory of any major British city, in which hundreds of people bearing my own surname will be found.
The Irish and the English are far more intertwined than they ever acknowledge officially, but privately we all know this to be true.'
In 'Irish Blood English Hearts' Joseph considers the complex cultural relationships between Britain and Ireland.
He writes letters to Queen Elizabeth and her great, great grandmother Queen Victoria (who last visited Dublin over 100 years ago) about the land that they will visit and the nature of the reception they can expect.
Producer: Rachel Hooper
A Falling Tree Production for BBC Radio 4.
Joseph O'Connor considers the complex cultural relationships between Britain and Ireland.