There now exists an easy, equal confidence and mutual respect between the people of the two islands, writes Mary Holland.
'He hasn't got a club but he's got a country." It was, I think, Andy Townsend who made this comment on Gary Breen's crucial goal against Saudi Arabia. But Gary Lineker took the words up like a mantra while the other members of the BBC's panel of pundits nodded enthusiastically.
A number of people have remarked on the warmth which the British media showed in their coverage of Ireland's World Cup progress, something which hasn't always been evident in the past. Why wouldn't they share some of the joy? A sizeable number of Mick McCarthy's team, including Gary Breen, speak with the accents of the English regions even as they proclaim their pride in playing for Ireland.
After the scenes in Dublin on Tuesday, it would be a brave fan who dared to suggest that Mick McCarthy is somehow less than fully Irish. Equally, he or she would need to be quite obtuse not to recognise that it was the manager's streak of stubborn Yorkshire grit which enabled him to pick his band of demoralised players off the ground after the Roy Keane fiasco and remake them into the team which so gladdened us.
For anyone like myself, born in England of immigrant parents from Cork and well accustomed to the sneer that I have no real understanding of Ireland, one of the pleasures of this particular World Cup tournament has been to see the continuous blurring of what it means to be Irish.
I don't think it's fanciful to suggest that this mirrors what has been happening to the relationship between Britain and Ireland over the past few years. There now exists an easy, equal confidence and mutual respect between the people of the two islands, which is one of the more important dividends of the peace process.
This is the start of the marching season in Northern Ireland and, inevitably, the coverage that dominates our media is of the problems associated with this time of year - ugly sectarian violence, another possible threat to David Trimble's leadership.
But at a deeper level there are stirrings of political change, due to the recent general election, which could affect the whole island. Fianna Fáil's hegemony may seem to be set in stone, but there is a gaping hole where the opposition used to be.
The sounds emanating from Fine Gael's leadership contest sounded like a death-rattle. Enda Kenny has an endearing boyish charm, but he has failed to articulate anything which sounds like a political programme, let alone a vision. Labour's plight is nearly as dire. Suggestions of a challenge to Ruairí Quinn wilfully ignore that the party failed to win votes due to an inability to convince the electorate that it offered a credible alternative.
There seems to be a consensus that an alternative opposition will be found in the smaller parties, particularly the Greens and Sinn Féin. The contours of politics in this State are changing, and these developments are already having an effect in Northern Ireland.
It is more than 20 years since a British government minister told me he could quite easily imagine a situation where Northern nationalists would elect representatives to the Dáil while unionists would continue to send MPs to Westminster. Lord Gowrie - "Grey" as he was known to anyone who talked to him for more than 10 minutes - was a rum sort of Tory minister. For a start, he had spent large parts of his childhood in Donegal, studied at Trinity College, Dublin, and had a deep knowledge of Irish history and literature.
I thought Grey Gowrie's speculation was utterly fantastic, which was foolish of me. Look at the events of recent weeks. Sinn Féin has successfully projected itself as an all-Ireland party, with serious ambitions for power on both sides of the Border. Senior figures in the SDLP now wish to follow the same route by establishing links with a major party in this State. That could be Fianna Fáil, although some SDLP members would probably prefer Labour.
Similar developments have been taking place on the unionist side. Last week, Frank Millar, this newspaper's London editor, reported that David Trimble and some of his senior colleagues had re-opened discussions with the Conservative Party about a possible merger. The UUP leader sees this as part of a strategy designed "to place Ulster Unionist interests in a UK-wide contest".
This recalls the older partnership between the two parties, ruptured when unionists felt Mrs Thatcher had betrayed them by signing the Anglo-Irish Agreement in l985. Now, in a vastly changed political situation, Mr Trimble believes this could be a way of giving the broader unionist community the reassurance it so desperately craves.
It is much too early to predict whether and how these developments might work themselves out. But we should not be alarmed by them. The Belfast Agreement has shown itself to be a remarkably flexible and resilient instrument for effecting political changes. This is shown at its best in the new and vastly better relationship between the peoples of these islands.