Ireland matters. If three and a half years of anguished debate about the Irish backstop, and the Good Friday agreement, have had any long-term educational value, it has been to teach us that Ireland is significant to the UK economically and politically.

We export more to the Republic than to China, including Hong Kong; and more than our three leading commonwealth partners – Australia, Canada and India – combined. Meanwhile, the century-old partition of Ireland continues to cast its baleful shadow over the United Kingdom in the form of the intractable sectarian politics of Northern Ireland, its history of violence and its precarious modern peace.

Consequently, the results of the Irish general election on Saturday matter, especially as they portend a significant shift in the balance of power. First indications from Saturday’s exit poll showed that there has been a near dead-heat between the two traditional parties of government, Fianna Fáil and Fine Gael, and a resurgent Sinn Fein, each with over 22 per cent of the vote. Though the Irish proportional system of voting is much fairer than first-past-the-post, 22 per cent of the vote does not necessarily translate into 22 per cent of the seats. The vagaries of the system will be exacerbated by Sinn Fein’s failure to stand as many candidates as the traditional parties have.

Ireland Election 2020: Sinn Fein gains suggest three-way tie Show all 23 1 /23 Ireland Election 2020: Sinn Fein gains suggest three-way tie Ireland Election 2020: Sinn Fein gains suggest three-way tie Sinn Fein candidate Donnchadh O'Laoghaire celebrates with supporters Reuters Ireland Election 2020: Sinn Fein gains suggest three-way tie Sinn Fein president Mary Lou McDonald speaks to the press at a count center in Dublin. Exit polls in the Irish general election suggest a three way tie between Fianna Fail, Fine Gael and Sinn Fein EPA Ireland Election 2020: Sinn Fein gains suggest three-way tie An activist dressed up as a giant stick of celery who targeted two Irish politicians at a polling station at Kilgarvan Central School in Co Kerry Peta/PA Ireland Election 2020: Sinn Fein gains suggest three-way tie Sinn Fein's Paul Donnelly celebrates with his mother Bridie after winning Dublin West Getty Images Ireland Election 2020: Sinn Fein gains suggest three-way tie Bonnie, a terrier cross waits for her owner outside a polling station in Drumconda Getty Images Ireland Election 2020: Sinn Fein gains suggest three-way tie Sinn Fein's Donnchadh O'Laoghaire was the first TD to be elected as he topped the poll in Cork South Central PA Ireland Election 2020: Sinn Fein gains suggest three-way tie Fianna Fail leader Micheal Martin is greeted by a supporter during the Irish General Election count at the Nemo Rangers GAA Club in Cork PA Ireland Election 2020: Sinn Fein gains suggest three-way tie Taoiseach Leo Varadkar casts his vote Getty Images Ireland Election 2020: Sinn Fein gains suggest three-way tie Sinn Fein candidate Aengus O Snodaigh with supporters in Dublin EPA Ireland Election 2020: Sinn Fein gains suggest three-way tie Counting begins in the Cork South-Central constituency Getty Images Ireland Election 2020: Sinn Fein gains suggest three-way tie Sinn Fein's Paul Donnelly celebrates with his mother Bridie after winning Dublin West Getty Images Ireland Election 2020: Sinn Fein gains suggest three-way tie Sinn Fein's Donnchadh O'Laoghaire with his partner Eimear, their four-month old baby Fiach, and their son Se, aged 9 PA Ireland Election 2020: Sinn Fein gains suggest three-way tie Counting staff PA Ireland Election 2020: Sinn Fein gains suggest three-way tie Sinn Fein supporters celebrating EPA Ireland Election 2020: Sinn Fein gains suggest three-way tie Sinn Fein President Mary Lou McDonald during the Irish General Election count at the RDS in Dublin PA Ireland Election 2020: Sinn Fein gains suggest three-way tie The count gets under way at Nemo Rangers GAA club in Cork, southern Ireland, on February 9, 2020, the day after the vote took place in the Irish General Election. - Irish officials started tallying votes on Sunday in a general election forecast to put prime minister Leo Varadkar's party in a historic three-way tie, after a surge from republican party Sinn Fein. Counting began at 0900 GMT after an exit poll predicted Varadkar's Fine Gael party, the Fianna Fail party and Sinn Fein all received 22 per cent of first preference votes in Saturday's election. (Photo by Paul Faith / AFP) (Photo by PAUL FAITH/AFP via Getty Images) PAUL FAITH AFP via Getty Images Ireland Election 2020: Sinn Fein gains suggest three-way tie President Michael D Higgins and his wife Sabina Coyne vote in the Irish General Election at St Mary's Hospital in Phoenix Park PA Ireland Election 2020: Sinn Fein gains suggest three-way tie Counting begins in the Cork South-Central constituency Getty Images Ireland Election 2020: Sinn Fein gains suggest three-way tie Leader of Ireland's Fianna Fail party, Michael Martin (R), and his wife Mary (L) pose for a photograph after voting at St Anthonys boys school in Ballinlough, Cork, in southern Ireland on February 8, 2020, as voting gets underway in the Irish General election. - Polls opened across the country at 0700 GMT, although a small number of islands off the west coast voted on Friday to allow for rough seas that could disrupt the transport of ballots by boat. (Photo by Paul Faith / AFP) (Photo by PAUL FAITH/AFP via Getty Images) PAUL FAITH AFP via Getty Images Ireland Election 2020: Sinn Fein gains suggest three-way tie Counting staff during the Irish General Election count at the Nemo Rangers GAA Club in Cork, Ireland. PA Photo. PA Photo. Picture date: Sunday February 9, 2020. See PA story IRISH Election. Photo credit should read: Yui Mok/PA Wire Yui Mok PA Ireland Election 2020: Sinn Fein gains suggest three-way tie Counting begins in the Cork South-Central constituency Getty Images Ireland Election 2020: Sinn Fein gains suggest three-way tie Counting begins Getty Images Ireland Election 2020: Sinn Fein gains suggest three-way tie Sinn Fein President Mary Lou McDonald, with local councillor Seamas McGrattan, arrives to cast her vote PA

Nonetheless, Leo Varadkar, the Taoiseach – who many of us thought was a more commanding figure in the Brexit negotiation than his British opposite numbers – looks to have lost power. His Fine Gael party, which had 50 out of 160 seats in the Dáil, and ruled in coalition with independents and small parties saw its vote share shrink from 26 per cent to 22 per cent. The main opposition, Fianna Fail – which had given tacit confidence and supply support to Varadkar – also lost some ground, which is a major disappointment since its leader Micheál Martin looked well placed to lead a new government. The final tallies, and a lot of haggling, will determine whether he gets his chance.

The two traditional parties have moved on a long way since they were defined almost a century ago by being on opposing sides in the civil war, after Irish independence. Fianna Fáil is the party of Éamon de Valera: once a bastion of Catholic and nationalist politics, and deeply conservative on social issues. Now it is a mainstream European social democratic and liberal party, (slightly) left of centre, and a sister party to the British Liberal Democrats.

Fine Gael is the party of Michael Collins, a revolutionary hero but loser in the civil war; now a mainstream European party, (slightly) right of centre. Its social liberalism is reflected in its leader: a gay man, the son of Indian immigrants. I dealt with leading figures in both these parties in the course of the Brexit debates, and it was difficult not to be impressed by people who are comfortable on the big stage of European diplomacy but also locally grounded in the parochial, backslapping culture of Irish politics.

But with all first preferences now counted, the big winners in the election were Sinn Fein, which dramatically increased its vote share from 14 per cent to 24.5 per cent. Until very recently, Sinn Fein’s crusade for a united Ireland and its links to the terrorism of the provisional IRA were seriously unfashionable in the south, which has prospered in Europe without the troubled six counties of the north.

So what has changed? In the south, Sinn Fein has repositioned itself as a party of the radical left. It appeals to students and the urban working class who have become disenchanted with the traditional political duopoly, and angry about deficiencies in public services, the harsh workings of the housing market and the inequalities which derive from both. Mary Lou McDonald, the party leader, is an articulate and approachable Dubliner (a convert from Fianna Fáil) and is – in terms of her public persona at least – far removed from her predecessor. The dour and rather threatening figure of Gerry Adams was hardened by a lifetime of conflict in the north and his association with the provisional IRA was a big political liability.

The emergence of a successful, rebranded Sinn Fein must lead us to ask whether the prospects of Irish reunification have increased. At first sight, they should have. Their success in the Republic reflects a trend in the north. The party can claim to have overtaken the DUP as the leading political force there. And Northern Ireland’s anti-Brexit majority includes former unionists, who now identify with Europe and Ireland more than Brexit Britain. Other, more fervent, unionists feel betrayed by the British government, which has negotiated a border in the Irish sea as part of its Brexit deal, prioritising continued economic integration with the Republic over that with Great Britain. Why should such voters continue to owe their allegiance to the UK?

And there is a small but growing group of northerners who have left behind tribal allegiances to vote for the liberal Alliance Party of Northern Ireland. They and others no longer subscribe to the strict social conservatism of the Catholic and Presbyterian churches, and on issues like homosexuality and abortion have seen that Ireland – like Britain – has moved on. Moreover, the underlying demographics of the north is slowly producing a majority who identify themselves as nationalist and Catholic (or Gaelic speaking) rather than Unionist and Protestant (or speakers of Ulster Scots).

But it takes two to tango. Even if Sinn Fein were to secure consent in the north for its objective of a border poll, and win it, the politics may prove more difficult in the south. One big reason is that Ireland is now richer than the UK, and much richer than Northern Ireland, reversing a centuries’ old economic inferiority. Official per capita GNP is €72,000 as against €31,700 for the UK and €24,000 for Northern Ireland. These figures are somewhat suspect because multinationals – who use Ireland as a tax-haven – declare large payments there, artificially inflating national income (what has been dubbed leprechaun economics). If the statistics are adjusted to correct this anomaly, the Republic is probably twice rather than three times richer than the north.

However the figures are calculated, the north is now the poor relation. The old stereotype that thousands of large catholic families would migrate in a united Ireland to live off the largesse of the better off north has disappeared into mythology. The question now is whether the south would want to subsidise a province acquired for largely sentimental reasons. It would require great generosity and national unity of the kind demanded of Germans in the 1990s to make it happen. And unlike Germany, there would be many thousands of sullen, resentful loyalists to the UK, resolved to fight the battles of the 17th century once more.

Large numbers of the southerners who are now voting for Sinn Fein do not share its nationalist ideology and are not interested in a messy reunification. The party’s success can instead be explained by Ireland’s emergence as a normal European country with a home-grown populist party of protest.

There is quite a lot to protest about. Although Ireland has recovered impressively from the collapse of its banks and the bursting of its property bubble earlier in the last decade, there have been casualties. Fiscal austerity has meant overstretched public services. A recovering housing market has led to unaffordable rents and house prices. Many of the economic casualties voted Sinn Fein.

The two established parties were committed to keeping Sinn Fein out of government. To do so they will have to ally with each other and perhaps the Greens, who had a good election and will use their bargaining power to demand greater action on climate change. But being out of power may suit Sinn Fein. Freed of the responsibilities of government, they can continue to feed off domestic grievances. And when the shockwaves from a hard Brexit cross the Irish sea, anger at Britain will feed a nationalist agenda, north and south. We may not yet have seen peak Sinn Fein.