ALTHOUGH academically selective, state-funded grammar schools were purged from most of mainland Britain in the 1960s and 1970s, they clung on in Ulster. And with good reason. Many are wonderful, and the Catholic ones in particular have been a route to the upper middle class for many clever children from that historically downtrodden group.

Yet these schools are also part of an education system that remains starkly divided on confessional lines. More than 90% of Northern Irish children attend schools that are mainly Catholic or mainly Protestant. At Lumen Christi in Derry, one of the best Catholic grammar schools, all pupils are encouraged to study religious education up to age 15, learning, for example, the history of clerical vestments.

Almost all outside observers of Northern Ireland see this unofficial segregation as a factor in prolonging sectarian antagonism. With tough budget cuts looming, the duplication caused by sectarianism looks harder to justify, and most public figures inside the province agree in theory that Catholic and Protestant youngsters should do more learning together. But the status quo has powerful defenders, on both sides of the sectarian divide.

Campaigners for integrated education complain of a wall of opposition from two main quarters. The first is the Democratic Unionist Party (DUP), for which most Protestants vote. Peter Robinson, the first minister and leader of the DUP, has spoken in favour of integrated education. But his party has little to gain from a melting away of sectarian division.

The second opponent, unsurprisingly, is the Catholic church. It has fought a skilful defensive campaign, standing firm on religion while also arguing that the Catholic grammar schools should be open to all Catholic pupils, not just the brightest. To some, it seems that the church is stressing equality among Catholics as a subtle way to preserve religious separation. A few schools have bent under this pressure and dropped their academic entrance tests. Others, like Lumen Christi, are resisting. On January 25th Archbishop Eamon Martin made a fresh plea to end selection.

In this, the Catholic church is oddly allied with Sinn Fein, the political voice of Irish republicanism. That party is anti-clerical at heart, and clashes with the church over gay marriage and abortion, yet it is also socialist. And so church and party are as one on the desirability of all-ability schools, although neither is in any hurry to see mixed-religion schools.

With one qualification. John O’Dowd, the Sinn Fein education minister, has overridden his civil servants’ advice and earmarked funds for a new Irish-language secondary school. In theory, most of these Irish-medium schools are non-religious and open to all, thus ticking the secular box. Yet out of the 5,000 or so Northern Irish pupils who attend them, only about 40 are from Protestant homes. They are hardly engines of integration.