The line of green tents looks particularly vulnerable against the sweep of the Northumbrian hills. There’s an autumnal bite to the breeze and grey clouds have spread across a previously deep blue sky.

Pupils from Farringdon School in Sunderland crowd around some makeshift tables, sniffily surveying lunch - a cold, rough-and-ready buffet of tuna, spam, salad, crisps and pickled onions. They’re tired from the previous night’s shenanigans, the compulsory ritual of school residentials - few have had more than two hours sleep - and a morning of hard work.

Nevertheless, they are content. One girl bounds up to Dave Miller, the school’s head of humanities, worse for wear himself after a night on patrol: “Sir,” she beams, “can we stay for another week?” This is the third year running that senior staff and year tutors from Farringdon School have spent the third week in September camping with the entire Year 7 intake who’ve just arrived from primary schools. The setting is Otterburn Hall, high in the heathy landscape of the Northumbrian borders.

It is not an undertaking they consider lightly. It’s a gruelling exercise, but one they regard as enjoyable and crucial to the success of children settling into the school. They want to reap the benefits that school trips can bring at the beginning of the school year and to include every child rather than the select few who can afford to pay.

“I should say this eclipses the pain of tutors getting to know their kids by two to three months,” says Mike Tunn, the burly cook and Farringdon’s head of upper school. A devotee of residentials, he gives up three weekends out of five during term-time to take children across to the Lake District and spends holidays taking groups to France and Spain.

“We do a lot of problem-solving activities. The emphasis of our residentials is pastoral rather than hanging from cliffs by a nostril. You can’t beat the living-together experience.”

Last year 850 pupils from Farringdon, a 1500-strong comprehensive, went on residentials of one sort or another. However, the Otterburn trip, which this year saw 287 eleven-year-olds bussed into the northern hills, is regarded as being particularly successful.

Half the year group travels out at the beginning of the week, the other half for the latter part. Pupils are charged Pounds 15 inclusive; the schools meets the bill for those who cannot afford it. The idea is for all pupils to get to know their teachers and to make new friends.

The trip means 15 teachers out of school for the week but colleagues are willing to cover because the benefits that Otterburn gives are so tangible.

Pupils visit Kielder Water reservoir, tour the dam and travel on a launch. Back at base they follow an art trail around the grounds of Otterburn Hall, studying architectural detail and dealing with simple perspective. Karen Pollock is fascinated by one of the hall’s bricked-up windows. She turns to me wide-eyed. “Do you think somebody was murdered in there?” she asks as her group sits with their backs to the kitchen garden to contemplate domestic decoration.

The gothic horror potential of this rambling Victorian manor has obviously made a deep impression on receptive minds. This tutor group scribbled solidly in their art trail work books for two hours as they toured the grounds, a degree of concentration most teachers would regard as unachievable in the classroom.

The school’s senior management backs the trip at such a crucial time in the school year on the understanding that precious lesson time will not be lost. As a result teachers make use of everything they do at Otterburn throughout the school year. “It becomes a reference point ,” says Jim Bullock, Farringdon’s assistant head of art who has made the trip for each of the three years. “I can say ‘Remember when we were at Otterburn we did this’.”

As well as the art trail, pupils follow woodland paths and go pond-dipping. John Robe, head of science and one of the initiators of the trip, says it makes the teaching of subjects like photosynthesis and the food chain so much more pleasurable and memorable.

“When I talk about trees and light out here they remember it, because it is such a special setting. I could talk about photosynthesis for an hour in the classroom and five minutes out in the yard at break time, and most of them would have forgotten it.”

John Robe grabbed pupils the previous evening as they emerged from the on-site disco, pointing out the star-spangled night sky. “We do an exercise on light pollution in the upper school. They would never see stars like this in an urban area. If it wasn’t for the fact that getting them to settle at night was so difficult, I would have had them all out staring into the heavens.”

The trip, he believes, is value-for-money in so many ways. Taking the whole year group pond-dipping more locally, for example, would cost almost as much as the entire Otterburn trip. “It just wouldn’t be economical.”

On their homeward journey pupils visit a Roman fort where they role-play as Roman soldiers, writing letters home to mum in sunny Italy complaining about cleaning out latrines in the cold, damp, windswept borders.

Dave Miller says: “A Roman study unit is part of the Year 7 national curriculum. Here we have nearly 300 children and they will all have had fieldwork experience in this topic. Every bit of this trip is made use of.”

As an exercise in English language, pupils keep an Otterburn diary. Ken Crann, Farringdon’s head of Year 8 who has been teaching in the school for 25 years, believes the Otterburn venture gives each child a significant kick-start in the school, and helps year group tutors to make rapid assessments.

“You get to know your kids very quickly - those clever kids who are going to walk off with everything, and those who are going to need a great deal of help. I think we wouldn’t achieve the same quality of understanding between teacher and pupil if we didn’t do this.”