"Having grown up in Catholic convents, I have a bit of a problem with their `Catholicism is the one true religion' attitude," says a former teacher from south Dublin who sends her three children to Protestant schools and admits to being "a bit of an atheist."

Despite her own unbelief, she thinks "if you want a child to grow up as a well-rounded person, a spiritual education is very important. It doesn't matter where it comes from as long as it tolerates other people." She finds that well-rounded education in Protestant-run schools such as St Andrew's in Booterstown and Rathdown in Glenageary.

"The idea of religion is just not important any more. Well-off people now want a well-rounded education for their children and know that so much is going on here: speech, drama, music, horse-riding, sailing, absolutely everything," says a teacher at Alexandra College.

"It suits modern, working parents that the school provides everything under one roof, and they just have to write a cheque to cover it."

The phrase "well-rounded", including religion or not, constantly crops up in conversations with Dublin middle-class Catholics about why they send their children to Protestant secondary schools.

Earlier this week it was revealed that 70 per cent of the day pupils and 90 per cent of the boarders at the Republic's premier Protestant girls' school, Alexandra College in the south Dublin suburb of Milltown, are now Catholic.

Most of them are Catholic only in the loosest sense. A teacher's query about weekly church attendance in a nominally Catholic south Dublin primary school recently elicited the response from a class of 35 10-year-olds that fewer than 10 of them were weekly Mass-goers.

The 20 or so Catholic parents with children at Protestant schools who were consulted by this reporter ranged from "fair-weather Catholics" to people who were frankly hostile to the whole ethos.

These are the new moneyed class of south Dublin who send their children to Kildare Place, Taney and Glenageary Protestant national schools and Alexandra, Rathdown and St Andrew's for their secondary education.

"The religious ethos is incidental. They send their children to Church of Ireland schools because they offer a good education. With Catholic schools taking fewer boarders, our boarding schools are particularly attractive," says one Protestant mother with children at St Columba's.

The latter's old-fashioned English public school atmosphere and £2,400-a-term boarding fees probably make it less attractive than most to middle-class Catholics.

The most cited reasons for Catholics sending their children to Protestant schools are, of course, the obvious ones: proximity and academic reputation.

Thus Alexandra's central situation in the inner south Dublin suburbs enormously enhances its other attractions, excellent facilities, a superb range of extracurricular activities (including 22 full- and part-time music teachers), and its reputation for sending students on to high-prestige, high-points courses, particularly at TCD.

Its waiting list is already phenomenal, and will surely disappear over the horizon if and when the Luas arrives at its gates.

Places at Rathdown are prized for the same reasons, plus the cosy "home from home" atmosphere, particularly in its boarding section. Here the proportion of Catholic girls is probably well over 50 per cent.

One Rathdown parent, a Northern Catholic, speaks of the near-despair he and his wife experienced when they were advised by a leading educationalist to send their 11-year-old daughter to a shabby, rundown community school in south Co Dublin.

They were seriously contemplating going back to Belfast to send her to Methodist College, Royal Belfast Academy or Catholic Fortwilliam until they discovered Rathdown, "a small, friendly school with a real sense of community and a good, strong headmistress."

There is an element of snobbery as well, especially in areas like Ranelagh and Donnybrook, which have been flooded with nouveaux riches flush with takings from the Celtic Tiger. Many Catholic parents there express a preference for a private, fee-paying school.

"They think they won't get a Dublin accent at a Protestant school," says one Protestant parent. A parent with leftish views worries that his daughter at Alexandra will have a view of a world in which "the poorest people only have one car".

Dublin Protestants don't seem too bothered by their schools' popularity with Catholics. "We don't feel threatened. No Protestant parent has ever come to me and said, I couldn't get my child into one of our schools because of it," says Ms Marie Danaswamy, president of the Protestant secondary schools parents' body.

They sometimes mutter about the "dilution of the ethos" or tell stories about the occasional uppity Catholic-turned-secularist parent who objects to a clerical headmaster wearing a dog collar.

OUTSIDE Dublin the situation is rather different. "There is a different approach in rural Ireland. There isn't the Dublin liberal thing," says Mr Adrian Oughton, principal of Wilson's Hospital, a school with a strong Church of Ireland ethos in Co Westmeath.

"If the kind of numbers of Catholics at Alexandra occurred here tomorrow the school would cease to exist."

About two-thirds of his students are Protestant, the great majority boarders, and they come from 22 of the Republic's 26 counties, a sign of the value the far-flung rural Protestant community places on maintaining its ethos through its children's education.

Schools such as Kilkenny College and Monaghan Collegiate remain more than 90 per cent Protestant. The boarders at Dundalk Grammar School are almost all Protestant, while the day pupils are mostly Catholic. One informed educationalist estimates the average proportion of Catholics at the Republic's Protestant schools at 3050 per cent.

There is some concern among Church of Ireland clergy, most of whom have little input into Protestant schools' decision-making because of their plethora of independent and semi-independent management structures, about the inflow of children of the new, secularised Catholic bourgeoisie.

"The Protestant ethos can comfortably accommodate the Catholic ethos," says one senior clergyman. "However, you can dilute the Church of Ireland character of schools to such an extent that it is no longer meaningful. You can accommodate to the point where you cease to exist."