Unionists have made much, in recent years certainly, of the "Ulster Scots" dimension. But tonight in Edinburgh it is the Irish-Scots dimension which will move centre-stage as the Taoiseach opens a new, and potentially crucial, chapter in the history of the relationship between the two countries.
Before delivering the prestigious Lothian European Lecture, Mr Ahern will attend a reception marking the establishment of a Consulate General of Ireland in Scotland. The move, being mirrored in Cardiff, marks a highly significant extension of Irish diplomatic representation in Britain. If Mr David Trimble and his colleagues are paying little attention as yet, one fancies that will not remain the case for long.
Soon after his appointment the Irish Ambassador in Britain, Ted Barrington, became aware of the limits of covering events in Scotland and Wales from London.
Mr Barrington, who played a very important role in the events leading to the Belfast Agreement, instinctively felt it was necessary to have people in situ to follow the politics and the evolution of events in both countries. That instinct heightened in the approach to last year's general election as the British Labour Party finessed its plans for constitutional reform in Britain.
The administrative assessment and the political happily coincided. The Taoiseach and other Ministers had separately concluded they should develop the Scottish relationship in particular. By the summer of last year, in anticipation of devolution in Britain and the hoped-for agreement on Northern Ireland, the first plans for consular offices in Edinburgh and Cardiff were up and running.
The size of two small embassies, the new consulates will replicate the work carried out by the main embassy in London, most crucially in developing and maintaining contact with the emerging Scottish and Welsh executives, with the parliament and assembly and the political parties, and in monitoring and reporting developments in both countries.
While there are potential synergies between the economies, Ireland, of course, remains in competition with Scotland and Wales for mobile inward investment, so the economic dimension will be important.
The cultural renaissance in Scotland is likened to what has been seen over recent years in Ireland. And, of course, the Consuls General, Dan Mulhall in Scotland and Conor O'Riordan in Wales, will each look after large Irish communities. Closer to home they will also assume importance as the two sovereign governments and the five separate "devolved" administrations (don't forget the Channel Islands and the Isle of Man) start to put shape on the British Irish Council, to be established under the Belfast Agreement.
The Edinburgh and Cardiff consulates will play their part in the expanded overall British diplomatic mission to ensure that all parties coming to the table know the Irish perspective on the issues of the day.
None of these developments should be seen as in any way threatening the emergent administration in the North. To the contrary, they represent a considered and enlightened response to the changing political landscape in Britain, into which, conveniently enough for Mr Blair, devolution to the North has fitted very nicely.
Nor are they predicated on any working assumptions as to where Mr Blair's constitutional revolution might eventually lead. Sources insist that what is happening now should be viewed in the context of devolution as defined and envisaged by the British government in London.
That is undoubtedly true, as far as it goes. But Irish planners are as aware as any close observers of the scene that great uncertainty attends Mr Blair's constitutional adventure. Certainly, they will be acutely conscious that leaders of political and intellectual life in Scotland are embracing more than ever the concept of a Scots identity, and that in Alex Salmond the Scottish National Party has a highly charismatic and effective leader.
The polls suggest Labour is recovering and that the SNP is unlikely to be negotiating Scottish independence this time next year. But in eight, 10, 15 years' time? Nobody knows anything for certain, save that independence is now part of the developing agenda.
And if Scotland finally goes its own way? That would not necessarily mean that England, Wales and Northern Ireland would follow suit. But it would, without question, force a redefinition of those relationships, and mark the end of the UK as we have known it.
Last April the Ulster Unionist leader had to accommodate himself to Mr Blair's very different view of the Union and to the changing face of Britain. Even before the Belfast Agreement has bedded down he must be aware, and the Irish Government's long view will sharply remind him, that Mr Blair's revolution has a long way still to run.