From the outside, it's hard to believe that St Mary's College, Derry, ranks as one of Northern Ireland's most successful schools. A collection of dreary buildings are packed onto the tiny campus surrounded by Creggan housing estates. The area is one of the least affluent in Northern Ireland and suffers high unemployment. Some 60 per cent of the 1,000 pupils - most from the nearby estates - get free school meals.

Inside, however, St Mary's is spotlessly clean and brightly decorated. "I do believe our students deserve the very best," says head mistress Geraldine Keegan, as she apologises for the quality of the buildings.

The girls themselves are immaculate and dressed in toning shades of blue. The school uniform is important and clearly it's something pupils are proud to wear.

Over the past decade, the school has won a string of awards. Just recently, St Mary's has achieved its third Charter Mark Award - the gold medal of public service in Britain and Northern Ireland. The school has been winning this award, which is held for a three-year period, since 1992 when it was first introduced by the then prime minister, John Major.

On top of this, St Mary's has also won a number of European and Northern Ireland awards, including the UK Schools Nomination for the European Alcuin Award, the National Training Award and the Northern Ireland Quality Award.

One of the most interesting aspects of this success is the fact that it is a secondary, rather than a grammar school. Northern Ireland, unlike England, Scotland and Wales, still retains the 11-plus exam which determines the type of education a pupil gets after the age of 11.

St Mary's takes the 65 per cent of pupils in its catchment area who are deemed by the 11-plus exam to be unworthy of an academic education. However, the school offers A levels and an increasing number of students are going on to third level. "Increasingly, we're attracting pupils who would normally go to grammar school," says Keegan.

Sixth formers Julie O'Connor, Denise McIntyre and Laura Jones all hope to go to university, perhaps to train as teachers. The three girls admit that they all performed poorly in the 11-plus, but later managed good GCSEs and are now hoping to do well in A levels.

"The 11-plus doesn't really mean anything," they argue. "It should be scrapped."

Most second-level students are reluctant to admit that they might like school, but here students are very positive that school is a good place to be. The proof of the pudding lies in the fact that the girls clamour to come back to school on Saturdays and to take part in special study weekends. Every year, St Mary's is forced to turn away large numbers of applicants.

"We see it as a great challenge for us to help pupils overcome the trauma of the 11-plus and to ensure that they develop to their full potential," Keegan observes. "To do that we use a wide range of interventions."

The Higher Education Liaison Programme (HELP) is a vital element in this, offering students a range of options including individual tuition, assertiveness training, residential courses, a homework club, social and study skills training and special training in maths and English. The school works closely with parents and the community, she says. The Take Your Parent to School day is an annual event in which the parents of first-year students spend a day at school with their offspring.

"It's one of the most exciting events in the school," says Keegan. "It lets parents see exactly what it's like for their children and gives them a better understanding of school life."

Evening courses enable parents to study maths, English and computing to GCSE level, while recreational courses, including art and cookery, are also available.

Parents, too, are trained to work as classroom assistants.

Keegan expects that a new course - Helping Your Child with Reading in the Home - will be as popular as Teach Your Child Maths. St Mary's also runs a writing group for parents and regularly publishes their work.

School management is constantly being upgraded. "We have adapted the European Business Excellence Model for use as a benchmark in the school," explains the school's head, who spent a year working as a senior manager in industry. "The most critical process for a school is its teaching and learning. If I can manage people well and release their potential, develop strategies and plan well, this helps staff deliver quality teaching and learning.

"To enable people to teach well you have to develop a climate where everyone wants to do the best for pupils."

Effective teamwork is essential. "We have a pupil-focused approach. Everyone is involved in addressing teaching and learning, including the support staff."

Meaningful delegation, where everyone feels valued is vital. So, too, is effective training and staff development. "We put a lot of resources into that," she comments.

School improvement teams and regular meetings of the senior management team, which always includes a junior staff member, help to keep everyone involved. "We carry out regular audits of pupils, parents and staff and then prioritise and address issues through the school improvement group."

Regular surveys of the community are also conducted. "Pupils also carry out surveys through the student council. They were instrumental in introducing Saturday school.

"We feel we are on a journey of continuous improvement which is never ending and which continues to make St Mary's a better place for pupils."