The announcement on the radio sounded like a continuity device from an old-fashioned drama: “There has been a serious earthquake in Islamabad.” It was 8 o’clock on Saturday, October 8 and I was having breakfast before making the final preparations for my trip to Pakistan.

A year ago I was invited by the Sisters of the Presentation, an Irish Catholic order founded in Cork, to visit their schools in Rawalpindi. I had written a book about a teaching method the nuns began using recently to unify the education of Christian and Muslim children. I accepted the offer and we agreed that October would be a good time to visit because autumns in this part of the world are mild and summery. Then the earth shook.

I phoned one of the two headmistresses, Sister Sheila Keane, and, to my amazement, got straight through; she was anxious that I should still come.

So that evening I boarded a British Airways flight to Islamabad, alongside the first British rescue team. The plane touched down seven hours later, and by the time I had reached the convent, five miles away, the rescue team were on television, digging in the ruins of a collapsed building in the centre of Islamabad.

The capital was largely undamaged, but the earthquake - 7.6 on the Richter scale -wiped out whole swathes of north-eastern Pakistan and Pakistani-controlled Kashmir. Schools were hit hard as the quake struck in mid-morning when lessons were in full swing; 400 children were buried alive at Balakot, 60 miles north of Islamabad.

The worst news came from the countryside, and over the following days it kept on coming. The initial death toll of 19,000 rose to more than 87,000 in a few weeks. Roads were cut off; in the northern hill villages, 75 per cent of the buildings had collapsed.

The Sisters of the Presentation run two schools, the Presentation and St Theresa’s, which together cater for almost 3,000 local girls - half Christian, half Muslim with a sprinkling of Hindus - aged four to 15. The schools were closed for three days following the earthquake. The girls stayed at home with their parents while the buildings were checked for structural damage (there was none), but the Sisters remained busy. With the teachers, they collected glasses, plates, bottled water, blankets and towels to take to local hospitals, where the injured had been flown in from hill villages many miles away.

I joined the Sisters on a visit to the children’s hospital in Rawalpindi.

Most of the 500-plus patients were surrounded by relatives, many of whom had travelled more than 100 miles to be there. Doctors explained the wounds; limbs had been lost, there were dreadful head injuries. The eyes of the young patients were utterly blank, as though the child inside was absent. At the centre of all the kindness and care were lives that had been shattered beyond imagination.

The roads from the hospital were busy, and at every set of traffic lights young people approached cars and buses to ask for money. Along the roadside we passed large tables covered in stacks of blankets and bottled water.

When earthquake victims leave hospital, they take a blanket with them - it may be their only possession. The sound of whirring helicopter blades was more or less constant, punctuated only by ambulance sirens and the sound of big squawking birds disturbed by the chaos. Aftershocks were predicted; some happened, others were imagined. The mood was one of jumpy stoicism.

Few are more stoical than Sister Sheila, who has been in Pakistan since her late twenties, and has been head of St Theresa’s for 33 years. A fluent Urdu speaker, she retains her Kerry accent and is full of energy. Rising at 5am to pray in the chapel, Sister Sheila is off to school in a taxi soon after 6am. She is humorous and matter-of-fact, and her practical skills came to the fore in the days after the earthquake.

The Presentation schools - founded in 1895 to teach the Christian children of British army officers based in Rawalpindi, the former garrison town once known as the “Aldershot of the East” - began to change in the mid-Sixties.

Among the many edicts to emerge from the great liberalising Second Vatican Council of 1962-65 was one welcoming non-Catholics into Catholic schools; this, combined with a wish to understand other faiths, prompted the nuns to begin studying Islam. Gradually they discarded elements of their traditional habits until finally they adopted the local shalwar kameez: cool in the hottest weather, as well as modest. Some of the older nuns still prefer white cotton clothes and a short veil.

Both schools are now private and charge modest fees: between Rs350 (about pound;3.50) and Rs800 a month, subsidised by the Order in Ireland. Sixty per cent of the teachers are Christian and 40 per cent Muslim, and only a minority are nuns. There is a shortage of qualified teachers so the nuns “grow their own”; about a third are former pupils.

But not everything has changed. The six nuns still live in a convent house within high walls that also enclose the Presentation school and a large garden; the entrance gates are locked and guarded. (This caution has a long tradition; the founder of the order, Nano Nagle, taught secretly in Ireland at a time when Catholic education carried the death sentence.) And the mission has remained the same; the Sisters of Presentation have never set out to convert people, but to give basic education. “Jesus told us to teach all nations,” says Sister Sheila. “And the Muslims are god-fearing, god-loving people.” The Presentation schools are so much a part of Pakistan that the post office issued a stamp for their centenary.

The Christian and Muslim pupils are separated for religious lessons, so the Sisters use a “positive values” framework to provide a unifying moral context for the children’s education. This multi-faith citizenship programme attempts to instil a practical understanding of concepts such as tolerance, hope, freedom, patience and trust. It was pioneered by Neil Hawkes, headteacher at West Kidlington primary school in Oxfordshire (see panel), in the 1990s and has since spread from Britain to other parts of the world.

The values programme has not been introduced fully at the Presentation schools -girls in Pakistan are traditionally not encouraged to have opinions or to argue, which makes it hard to hold open discussions about concepts that require personal reflection and disclosure - but the teachers are convinced of its worth. “It has brought a positive change,” says teacher Noreen Silas.

On the Thursday after the earthquake, the girls return to school, arriving in the Presentation convent at 6.45am, chatting happily, apparently without apprehension. By now we are accustomed to the clatter of supply trucks, donkey hooves and sirens, and to the helicopters. By 7.15am, the girls are assembled in lines outside to listen to Sister Julie Watson, head of the Presentation school, say a prayer. They then sing a hymn and listen respectfully to the Pakistani national anthem before filing off to their classrooms to the recorded strains of Celtic country dance music.

The current value word is unity, and children from Class 8 give their definitions: “thinking in the same way”; “everybody helping towards one result”; “working together”. They also give examples of united action, such as, “we are all collecting for the sick people”. The teachers decide to keep the word “unity” for an extra week, as it is so relevant to the catastrophe.

Class sizes of 45-plus are not uncommon here, but Sister Julie gives her own example of unity in action by offering places to children from Muzafarrabad, the capital of Pakistani-administered Kashmir some 30 miles away, which has been destroyed. In the classrooms, the children work as normal, bar the occasional evacuation drill. Four-year-olds throw themselves enthusiastically into their English lessons - literally in some cases as phonics teaching involves them standing up to make letter shapes and chant spellings together. Learning English is recognised as a means to a better career, and by the time they are seven or eight, the girls can ask questions about fashions, food, and family.

The 10-year-olds in Sister Bina’s class talk in English about Pakistani culture. “Food in Pakistan is famous throughout the world,” says one.

“There are thousands of restaurants.” “Can anyone spell restaurant?” asks Sister Bina. Many hands go up; the second girl to answer gets it right.

Unity certainly seems the appropriate word to describe this kind of learning.

As Noreen Silas says: “We have diversity here, even different sects within a single religion, and values bring them all on to the same ground. People are also becoming more materialistic, and moving away from religion. This helps them to have an alternative view.”