Surrounded by four peaks, each more than 8,000 metres high, Concordia is a truly stunning wilderness in Pakistan’s Karakorum mountain range, at the junction of the Baltoro and Godwyn Austen glaciers. It is no surprise that the area has been called the “throne room of the mountain gods”. Towering above the other giant peaks is K2, the world’s second-tallest mountain.

This was the sight awaiting 16 pupils from Clifton College as they reached the climax of their trek to K2 base camp, 5,200m above sea level. They were the first school group ever to reach it.

A two-day bus journey, eight hours by jeep and eight days’ hard walking are needed to reach Concordia from Islamabad. But this amazing trip seems anything but onerous. As the bus makes its way up the Karakorum highway, the mountains become higher and more closely packed. Grassy slopes give way to rocky outcrops and towering peaks.

The road, begun in 1996 in a bid to link the Pakistani capital with Kashgar, in newly friendly China, is a marvel of engineering. Some 1,200km long, it was a joint Sino-Pakistani project that took 13 years to build, and many lives were lost to treacherous weather and working conditions.

The road itself is safe enough, but the area is home to bandits, over whom the authorities have little control. Indeed, one reason for building the road was to increase control over the area.

Villages en route offer the group a fascinating glimpse of Pakistani life.

Young and old men sporting traditional salwar kameez and dyed-red beards pass endless hours smoking cigarettes and drinking tea with friends. The few women visible on the streets are covered from head to toe in the burqa.

It takes a while to get used to the piercing gaze of the locals, which is usually more inquisitive than hostile.

Despite the language barrier, a strong bond develops between the group and the porters. The pupils admire their physical toughness and their outlook on life.

Dan, 19, the oldest pupil on the trip, says: “It’s striking when you consider that they spend the day carrying 25kg on their backs.”

Geography teacher Martin Williams, who organised the trip, says: “There are preconceptions about countries, and on a trip like this stereotypes are challenged.”

With a big group unused to local food, and with oxygen levels at K2 base camp at just half those at sea level, sickness is par for the course. And there were other hardships. Temperatures vary from 40C in the midday sun to - 5C high up on the glacier at night. But even the worst-affected feel the hardship has been worth it.

“The sense of achievement for pupils is fantastic,” says Martin Williams.

“Some in the group weren’t sure they could do it. The fact that pupils have done this will stay with them all their lives.”

Guide Ali Murad was a vital ingredient in the trip. A former high-altitude porter, he has made the trek to K2 at least twice a year since the late 1970s. His local knowledge and friendliness made him an integral part of the group. Certainly, without expert advice many would be wary of such an ambitious and unpredictable trek.

“A risk assessment is difficult on a trip like this,” says Martin. “You need to use a reputable company. Himalayan Kingdoms has an impeccable safety record. Its reputation rests on the choice of good agents abroad.”

Martin is a trained mountain leader and has climbed Mont Blanc. He stresses the importance of asking the right questions before the trip. Even then, there can be unforeseen difficulties.

“The route we took was much more dangerous than I expected,” says Martin, although he adds that he would not hestitate to recommend the trip.

“There were parts where the bridges weren’t great, and there were places where mistakes could have had serious consequences.”

As well as safety, there is the question of cost. This trek cost pound;1,850 per pupil, but a series of fundraising events helped to ease the burden for the Clifton pupils.

Martin says: “If you plan a good fundraising strategy, you can get a lot of the costs down. And it’s well worth it - a trip like this is a life-changing experience.”

Himalayan Kingdoms returned to Pakistan this summer after a change in Foreign Office recommendations. For more information telephone 0845 3308579;email: info@himalayankingdoms.com;www.himalayankingdoms.com