‘This school trip to BORNEO (I shit thee nay) costs THREE THOUSAND FIVE HUNDRED ENGLISH POUNDS,” began an animated conversation on Twitter this week. The author of the tweet was a mother whose 15-year-old son had been invited by his school to travel to south-east Asia. Was he at Eton, one puzzled respondent asked. No, she replied, it was her son’s “bog standard secondary”.

Expensive school trips to far-flung corners of the globe are fast becoming the norm, not just in elite, private schools, but in ordinary state secondary schools up and down the country. Other contributors to the Twitter conversation told of trips to Japan, Madagascar and Cambodia, all costing in the region of £3,000. There was a netball trip to Sri Lanka, and an opportunity for some lucky children to travel to Uganda to see gorillas and help build a school, for a minimum price tag of £2,800. Other school destinations now include New Zealand, China and the Caribbean; there are trips to the Galápagos, the Arctic and Namibia. Really, it seems there is nowhere on the planet that is out of the question.

The mother whose son might be off to Borneo spoke to me but chooses to remain anonymous. “My view is it’s only really accessible for families with a large disposable income. Also, are children too young for these once-in-a-lifetime experiences?” Even more modest trips are out of many parents’ reach, she says. “I think it’s a huge ask of people, and they feel under pressure.

“The school does less adventurous trips, too, but even they are £200+ for a trip to a river in the next county.” The Borneo trip involves working with local communities, helping wildlife and building roads – but she wonders if her son would be better off going InterRailing.

Other parents are similarly concerned about the cost and divisions the trips create between those students who can afford to go, and those who can’t. Another mother, who also withheld her name, says: “The end-of-year trip for year 7s was a coach trip to Paris and staying in a youth hostel for four nights and cost more than £500 per child. It would have been very hard to say no as most of the kids were going. But £500 is a lot of money, especially if you have more than one child.

“I admire the initiative but it put huge pressure on families who could not afford £500 trips to cough up or let their child miss out on bonding and educational trips. Not to mention the social pressure of being seen by peers to be too poor to pay.”

Another mother, whose 14-year-old daughter is at an outstanding academy, has already paid for her to go on a five-day trip to Spain to support her GCSE studies (£600); she has a two-day media studies trip to London in February to see a West End show and visit Harry Potter World (£230), and next year has been invited to go to New York. “This is £1,300 for a three-day visit that is not even linked to any curriculum studies,” she says, adding that her daughter will also be expected to go on a geography trip to either Iceland or Pompeii (cost as yet still unknown).

“This is without the day trips and Duke of Edinburgh excursions.” she says. “We live in quite an affluent area and I think it is assumed the parents will just keep paying out for these experiences. I’m a teacher and in favour of getting kids out of the classroom but I can’t help feeling that these trips are ‘jollies’ rather than educational experiences. On the other hand, the school gets amazing GCSE results so maybe they’re on to something?”

Teaching unions have spoken out on this worrying trend. NASUWT says expensive school trips fall into a wider concern about parents increasingly being asked to pay for more and more aspects of their children’s education, such as “voluntary” cash contributions and access to music or drama.

A 2018 survey by the union that questioned 4,000 parents and carers about the cost of education found 15% of parents said they were unable to allow their child to participate in an educational trip or visit in the past year due to the cost, and more than a quarter said their child was unable to participate in non-curriculum related trips such as residential, foreign or end-of-term excursions due to the cost.

Geoff Barton, the former headteacher at King Edward VI upper school in Bury St Edmunds, Suffolk, and the current general secretary of the Association of School and College Leaders, says where there is a curriculum justification for a school trip, he is broadly supportive. Where he is less enthusiastic is when the trip is little more than a holiday, without any curricular benefit.

At King Edward VI, A-level biology students go on a trip to Indonesia to study marine biology at a cost of about £1,200. Part of the condition of running the trip, however, is that the students have to raise their own funds through charity events over a two-year period before the trip. “We always felt it was pretty significant that they were raising their own money and children from a wide range of backgrounds were able to participate.”

‘I worry we do too many of these trips’ – Vic Goddard, principal of Passmores Academy. Photograph: Graham Turner/The Guardian

There is also an annual exchange to Shanghai (around £800), where 30 students travel to China and the same number of Chinese students make the reciprocal journey. Again there is a fundraising element, and the school also ensures that one of the places is provided free of charge to a pupil who would otherwise not be able to participate.

“People should be wary of jumping to conclusions about these trips,” Barton says. “We would get students at the beginning of year 10 or 11 and say – ‘In two years’ time we will be going to X, Y or Z. Here are the fundraising activities you can do.’ And I think all those kids would say the buildup to it and all the effort they put into was a really important part of the trip.”

As a schoolboy, Barton never went on a residential school trip, either in the UK or further afield. Day trips to Chester zoo and Ironbridge in Shropshire were as far as he got. “But the world’s a different place and education really ought to be reflecting that,” he says. “Most schools will be doing anything they can to find ways of supporting children from disadvantaged backgrounds. There’s something about taking a child out of their environment.

“People may look at this and think – well, this has gone to extremes. But if there’s a curriculum justification for it, if there’s a justification around building leadership skills or character, or cultural reasons, and if the pupils are involved in raising the money themselves, it’s hard to argue it’s a bad thing.”

Barton, who left his headteacher role last year, says he fears the current crisis in school funding might be making it more difficult to support disadvantaged children to go on trips. Budgets in schools have been cut by 8% in real terms since 2010. As a result, so-called pupil premium money – additional funds provided to a school to support children on free school meals – that might previously have been used to pay for disadvantaged children to go on school trips, is now being used “to hold together a fragile budget”.

Vic Goddard, the principal of Passmores academy in Harlow, Essex, which was featured in the Channel 4 documentary Educating Essex, says when he arrived at the school 17 years ago, there were no residential trips at all. About 36% of the children who attend Passmores are deemed to be disadvantaged and teachers felt very reticent about putting on trips. “The first thing I did was arrange a ski trip for the kids. I gave them 18 months to pay it off. The maximum anyone would have to pay was £50 a month.”

Opportunity of a lifetime … children get to stroke a giant tortoise in the Galapagos Islands. Photograph: inga spence/Alamy Stock Photo/Alamy Stock Photo

As a boy, the only trip Goddard went on was a ski trip to Italy and he wanted his pupils to have the same opportunity. “I wanted to break the feeling that our kids could not cope with that sort of environment; I wanted to open up the community’s eyes to the fact that the world’s a big place. Seventeen years later, I worry that we run too many of these trips.”

In addition to the regular ski holiday, the other school trips on offer at Passmores include a visit to the battlefields of northern France and a water sports trip to the south of France, but Goddard remains acutely aware that for some families, it will very hard – if not impossible – to pay. “How do you make sure it truly is an opportunity for everybody?” he says. “Keeping that at the forefront of every opportunity has been something we’ve tried to do, but no matter how much we do that, there’s still going to be some who feel they can’t participate.”

To give every child the best possible opportunity, Goddard helped set up a charity called No Child Without to provide financial support for young people across Harlow in order to help them access educational and extracurricular opportunities that would ordinarily be beyond their means. Some children have had their ski trip entirely paid for out of the funds, other trips have been subsidised. “However, I still battle my angst about it,” says Goddard. “I know how wonderful an experience it is for the kids. I absolutely want them to go and get that experience. But you also don’t want a kid to feel worse because they can’t go.”

He satisfies his anxieties by giving his families “ages to pay”; and the most expensive trip he is prepared to run is the £900 ski trip, for which the charity has already funded seven pupils who wouldn’t otherwise have been able to go. “I don’t think we shouldn’t have trips. It’s part of a rounded education.” But he wouldn’t ask his parents to pay £3,000 for a trip. “If they can afford it, they should do it as a family.”

Pupils at Harrogate grammar school in North Yorkshire have in the past travelled to the Galápagos Islands (£1,700) and Uganda (£1,200), as well as skiing (£1,200 in Europe and £1,300 in New England, US), a three-day trip to Le Touquet in France (£200-300), and a year 8 trip to the Lake District that the school subsidises when families cannot afford it. The school’s chief executive headteacher Richard Sheriff says he and his governors have debated long and hard about the affordability of such trips. “We know the value of trips and visits and cultural opportunities to young people. If we do an expensive trip … we give plenty of notice so families can save for it. Most families could never afford to do such a trip together, but this way perhaps one child is able to have that experience that they would never otherwise have.

“We feel worried when these trip costs are high and we worry about those who miss out. But where are you going to draw the line? Is it £5,000? £500? £50?”

Exploring the Borneo rainforest. Photograph: Jodie Griggs/Getty Images

The Child Poverty Action Group (CPAG) has become so concerned about expensive school trips it has launched a project called Costs of the School Day to highlight the problems that children and their parents encounter financially in school. The charity is working to help schools remove the barriers that prevent children from taking part and ensure that they are not stigmatised if they come from low-income homes.

“It’s illusory to think that every family has a few hundred pounds – let alone thousands – for school trips,” says Alison Garnham, the chief executive of CPAG. “Some haven’t got money for after-school clubs, never mind foreign jaunts. It’s horrible for parents to have to say ‘no’ to their child when a trip invite comes home, and of course the risk is that children who have to forego trips feel excluded and embarrassed.

“Schools do need to be mindful of the fact that expensive trips will debar some pupils from taking part so they should ensure that every child is funded to go. Surely all children should be entitled to what’s offered in school.”

The charity is urging schools to offer only free or low-cost trips and suggests developing ties with local community groups that can help with transport or venues, to try to ensure that children are not stigmatised if they come from low-income households.

“Our latest Cost of a Child study found even families with two parents working full time for the ‘national living wage’ are 11% (£49 per week) short of the income the public defines as an acceptable, no-frills living standard. A lone parent is 20% short of that minimum living standard. Schools should think hard before offering trips that are way out of reach of some of their pupils.”