It has been a long time coming for Kingham Hill School: in October, star pupil Sam Xhu will be the first student to go on to Oxford in around 15 years.

The young mathematician will be among only a tiny handful of pupils to go to Oxbridge since the school’s most notable alumnus, former schools minister Lord Adonis, who attended the school while being brought up in a local authority children’s home in the late 1970s.

Once branded the “Borstal on the Hill”, Kingham has not in the past been well known for its academic prowess, so Sam’s achievement is more than a glimmer of hope for a fee-paying school hoping to double its numbers in the next 10 years.

Even for a determinedly non-selective establishment with a sizeable proportion of special-needs pupils, academic results remain a cornerstone of every school’s reputation. Cash-strapped parents want to know if they are getting value for money, especially as they feel the effects of the global economic downturn. Elegant buildings and country air are not enough to entice them.

But while other small, historic schools have withered and died in the recession, Kingham Hill is in the middle of an ambitious transformation, defying the downturn by making the most of its strengths and addressing its weaknesses.

Far from giving up and selling its premises to a hotel chain, the school, and the charitable trust behind it, is determined that it will thrive and return to its roots by providing increasing numbers of bursaries to pupils from deprived backgrounds. It already dedicates #163;840,000 from its annual fees income of #163;5.5 million to discounts and bursaries, but the school would like to provide more. Currently,80 of the 260 pupils have free or assisted places.

Lord Adonis, recalling his time at the school, says his time there gave him “all I lacked in life outside: stability, friends, values and a sense of self-worth and self-belief”. His experiences made him a vociferous supporter of boarding for young people from difficult backgrounds. The school is delighted that new Education Secretary Michael Gove has also expressed support for sending looked-after children to boarding schools. This is likely to be a debate that continues as Mr Gove beds into his new job.

Set up in 1886 by philanthropist Charles Edward Baring Young, the school, set on a hilltop in 1,500 acres of glorious Cotswolds countryside, initially took impoverished boys off the streets of London to give them a start in life.

The youngsters at Kingham Hill Homes For Boys, as it was known, were given a suit, boots and a Bible. They tilled the soil of the school’s farm, learnt carpentry and followed a regime of self-sufficiency. None of the pupils paid fees and by the 1850s the money from the benefactor’s legacy was beginning to run out.

Difficult decades followed in which the school acquired its nickname “the Borstal on the Hill” as local authorities sent Kingham Hill troubled pupils who had experienced problems elsewhere.

In the 1980s, the school became co-educational, and attempted to rebrand itself as a special needs school. But by the 1990s, the roll had slipped to 190 and bumped along at that level for some time.

However, with the arrival of a new headmaster, the school is heading for change. Reverend Nick Seward was appointed in 2008 to devise a 10-year strategy to take the school into the 21st century.

With no teaching qualification and just six years’ experience of teaching at the high-flying Magdalen College School in Oxford, his appointment could be construed as a gamble.

But the dynamic 39-year-old clergyman has the energy, and the faith, to pull off the challenge of boosting numbers to 400 by 2020.

The school already helps a number of pupils from “backgrounds of extreme deprivation”, says Reverend Seward, but he admits there are also those of “immense privilege”. The ultimate goal is for the latter to pay for the former.

A fundraising campaign aims to raise #163;5 million for a new academic building, and the school is looking to former pupils for help.

“We have a compelling history and the alumni and trustees are very supportive,” Reverend Seward says. “The alumni want to continue to support children like themselves. This was always a school that had potential. It had a poor reputation academically; when I arrived there was a lack of expectations.”

When he took up post, Reverend Seward says the school was allowing almost all children to to sit A-levels.

“Some kids were getting two Es, which is a waste of time. Because they weren’t academically strong enough, we have been finding a better use of their time. We introduced a minimum of five Cs at GCSE to qualify for A-levels.”

GCSE results were poor in the late ‘90s, he says, but A grades increased from 67 per cent in ‘07 to 85 per cent in ‘09. Last year, 76 per cent of pupils got five grade A-C, including English and maths compared to just 62 per cent in 2008.

Pupils can now study for a range of A-levels in “hard” and “soft” subjects, and OCR National Diplomas in business and sport are also available. But the curriculum is not the only area of change. Situated in a very affluent area of Gloucestershire, the school has expanded its day-school provision and school transport and has axed Saturday school.

It is also exploiting its proximity to the RAF’s Croughton communications base by running an American studies programme, for the children of US service personnel on the base.

The programme allows pupils from the US system to follow a tailor-made curriculum in which they study for GCSEs and A-levels, but have all their work recognised when they return to the US.

Kingham Hill, like many other private schools, has recognised the value of the international market. Although it restricts international intake to 15 per cent of its pupils, its attractive location and homely atmosphere is appealing to overseas parents.

The shiny prospectuses make it all look easy, but the only proof of success will be the expansion of the school rolls. But experts predict that the full effects of the recession will not be felt in the independent sector for another couple of years.

While Reverend Seward insists the strength of the school’s trust means there is no danger of the school closing, he says times are hard.

“It’s a very very difficult time - you’re fighting for every pupil. There will be difficult decisions to be make,” he warns.