The monarch is so central to the sense of identity felt by many unionists - and so antithetical to that of many nationalists - that it is tempting to wonder whether the passing of the Crown from mother to son will have a destabilising effect, as it may do in parts of the Commonwealth. But Northern Ireland is in a different category; the question of the Union has dominated politics there for half a century.
Some would say it has been the main question for the full 100 years of Northern Ireland's existence.
So, positions and identities are more firmly established - people tend to know where they stand regardless of the Crown. The monarch is a symbol of Britishness and not the reason for it.
In fact it is stronger currents which are destablising Northern Ireland's berth in the United Kingdom; Brexit is one, Boris Johnson's Northern Ireland Protocol another.
And perhaps more significantly next week, on the day after the Queen's funeral, we will get the results of the latest census. It may show that for the first time Catholics outnumber Protestants in NI.
That does not mean that a referendum on a united Ireland - a Border Poll - is close. But it may be getter closer. That is the context for the King's visit.
His accession is unlikely to weaken the Union, but despite his trip there today, he may not be able to do much bolster it either.
The remarkable life of the Queen remembered and the King's inaugural speech analysed in our latest episodes of What You Need To Know