"The general view here was that it was a great success, " said Con O'Donoghue, the school's deputy principal. "The atmosphere has changed; the girls and boys seem to work well together and I don't think anyone here has ever had cause to regret it."

St Flannan's is one of many boys' schools around the country that have opened their doors to female pupils in recent years, with the idea that girls can be a good influence in a boys' school.

But this is not a phenomenon that girls' schools have embraced. In fact, in many areas, girls' schools have actively resisted amalgamating with their male counterparts. While parents are happy to send their boys to mixed schools, there is a reluctance among many to do the same with their daughters.

Despite the fact that there are approximately 15,000 more girls of post-primary age than boys, it is boys who continue to outnumber females in mixed schools. And in almost all areas, there are more girls' schools than boys', as singlesex education for females continues to thrive.

The well-known research suggesting that boys perform better in co-ed schools while girls get on best in single-sex schools continues to hold sway with many parents, despite the fact that co-education is now part of government policy and is seen to be best international practice.

"It is true to say that there are definitely still parents out there who prefer their daughters to get a different kind of education, generally in a convent school, " said Pat O'Riordan, principal of Portmarnock community school, Dublin, where boys outnumber girls 60:40. "It's really a parental decision in the end, but we find there is no difference in how the boys and girls perform. One year the boys will be stronger, the next year the girls will do better."

Ireland has by far the highest proportion of students attending single-sex schools in Europe. Forty-four per cent of Irish students attend singlesex schools, compared to fewer than 5% of students in most European countries.

And 50% of Irish girls go to a single-sex school while just 37% of boys do.

This is set to change over time as the Department of Education has recently started to replace old schools with co-educational ones.

"This policy does not preclude the provision of replacement schools for existing single-sex schools where the particular circumstances warrant it and where this is in accordance with the wishes of parents and management bodies, " said a spokesman.

"However, the vast majority of new schools are co-educational."

Of the 33 new post-primary schools set up since 2000, 29 are mixed. In Ennis, when all of the schools in the town decided to go co-ed, only the girls' school, Colaiste Mhuire, resisted. It has retained a healthy population of approximately 600 pupils while the other schools have around 200 girls each.

In Roscommon town, plans to amalgamate the Christian Brothers' school and the Convent of Mercy girls' school have been met with stern resistance from parents.

"The girls' school, which was set up in 1929, has served the community well over the years and it has gone from strength to strength in that time. Why fix something that is not broken? , " Mary Regan of the convent's parents' association told local press recently, adding that girls tend to perform better in all-girls' schools.

At St Gerard's co-educational school in Bray, there is strong competition to attract girls. In its catchment area of Dun Laoghaire/Rathdown, there are 13 flourishing girls' schools compared to just seven boys' schools. With a school population ratio of 60:40 in favour of boys, St Gerard's feels it is doing well.

"What we have actually found in recent years is that we are getting more girls joining the school, " said principal Tom Geraghty. "I think parents are becoming more independent-minded in that respect and they are looking at their children's needs rather than the perceived norm. Not all students are suited to mixed education, but it works very well for the majority."

In co-ed schools, teachers find that girls tend to mature more quickly than the boys.

"The girls get focused on their studies a lot quicker, " said Geraghty. "They tend to settle down quicker while the boys take a little longer. But it's like a 100-metre sprint.

There's little between them in the end and there's certainly no way to tell who performs better."

Statistically, girls are now out-performing boys in almost all Leaving Cert subjects, although no comparisons have been made between girls from single-sex and co-educational schools. This year, girls did better than boys in all of the supposed male strongholds of maths and the sciences.

At St Flannan's, teachers were surprised to discover that music, introduced when girls entered the school, became far more popular with boys.

"It was funny, because we hadn't thought it would be that popular with the boys, " said Con O'Donoghue. "And when we introduced home economics, we got a few takers from the boys for that as well."

Parents who choose co-education for their children can often be driven by practical considerations, he believes.

"I think a lot of it is about location, " he said. "Bringing the boys and girls to the same school makes more sense to many parents than driving them around to different places. In my view, a lot of parents are driven by pragmatism."

And although girls' schools continue to be the first preference for many parents, Tom Geraghty believes that other factors are beginning to take over.

"Class size, subject availability and school facilities are definitely beginning to play a bigger part in parents' choices, " he said. "And while it's certainly true that girls have a calming influence on the boys and put an end to a lot of laddish behaviour, co-education is also good for girls. The argument for and against mixed education is definitely getting tighter and that's a good thing."

St Conleth's: minority of girls 'smarten the boys up' MORE than 35 years ago, St Conleth's College in Ballsbridge, Dublin, decided to allow girls to attend the school at senior cycle. Initially, it took girls from the nearby Ms Meredith's school for applied mathematics and science, before deciding to accept girls full-time. Since then, it has had an average of 20 girls attending the 200-pupil school every year.

"We find that girls have a very good mollifying influence on the boys, " said school principal Peter Gallagher. "They tend to smarten the boys up and they also do very well themselves. They are very much in the minority, but a lot of them come because their brothers or fathers were in the school. We find it really has its advantages at senior cycle." In fact, to date the school has celebrated six marriages between former pupils who met in school at the tender age of 16.

"These were pupils who met in fifth year and eventually fell in love and married in their 20s, " said Gallagher. "Some of them are sending their own children to St Conleth's now, both boys and girls, which is always nice."

Other parents move their girls into co-education at senior cycle because they feel it will be good for them socially, he said.

"It benefits both boys and girls, we find. There's a good rapport between the students and there's a bit of academic rivalry, of course. The girls tend to settle in quickly here and they retain their allegiance to the school long after they have left us."

Girls-only schools supply more university students Top 10 university feeder schools:

1.Gonzaga College, Ranelagh, Dublin 6 (boys)
2.Colaiste na Coiribe, Tuam Road, Galway (co-ed)
3.Mount Anville secondary school, Dublin 14 (girls)
4.Colaiste Iosagain, Booterstown, Co Dublin (girls)
5.Ursuline secondary school, Thurles, Co Tipperary (girls)
6.Colaiste Eoin, Booterstown, Co Dublin (boys)
7.Laurel Hill Colaiste FCJ, Cnoc na Labhras, Limerick (girls)
8.Loreto College, St Stephen's Green, Dublin 2 (girls)
9.Sandford Park School, Ranelagh, Dublin 6 (boys)
10. Holy Child secondary school, Killiney, Co Dublin (girls)

MOST of the top 10 university feeder schools in the country are all-girls' schools, with six of them providing the highest percentage of students to thirdlevel education. Just three boys' schools made it on to the list, while only one co-ed school, a Gaelscoil, appeared.

Whether girls' schools dominated the top 10 list because girls outperform boys in the Leaving Cert, or because girls do better in single-sex schools, is not known. However, other factors such as fees, class size and an ethos emphasising academic achievement are also likely to have played a role in the results. And the number one school in the country is an allboys school . . . Gonzaga College.

Ireland has by far the highest proportion of single-sex schools in Europe; in many countries single-sex education is virtually unheard of.

In 2002/2003, 44% of all pupils in Ireland were educated in single-sex schools. In 16 of the 25 other countries for which data was available, there was no single-sex education at postprimary level at all. These included Denmark, the Netherlands, Greece, Portugal, Norway, Iceland and Sweden.

In the remaining nine countries, very small numbers of 15-year-olds were educated in single-sex schools. In just two countries other than Ireland, more than 5% of pupils were in same-sex education. These were Belgium, which had just over 5%, and Luxembourg, with 10% of pupils in single-sex schools.