In ponytails and pink nail varnish, Katie, Amanda, Chloe and Maria are sitting round a table in their school hall, planning an outing. Clubbing perhaps? A trip to the multi-screen cinema complex? Hanging round the local shopping centre. In fact, this Year 9 “girl gang” are planning a 15-mile hike over Box Hill in Dorking, Surrey, which they will undertake over two days with a night’s camp in between. They’ve worked out the route on an Ordnance Survey map and are now considering the calorie content of sausages, noodles and Hot Crunch pudding. All their food will be carried on their backs and must justify itself in energy terms.

Chloe and Co are not the type of young people who spring instantly to mind in connection with the Duke of Edinburgh’s Award. One of them is perilously close to permanent exclusion after a violent incident with another pupil, and the only career ambition they can come up with between them is that Maria might want to train as a hairdresser “just for something to do when I’m indoors”.

Here at Ashford High - an 11-16 comprehensive on the edge of Heathrow Airport where the girls say there’s “hardly nothing” to do outside school - the award is being used to reach young people on their own terms. This girl gang have their sights set on at least the silver medal. “We want to keep going,” says Maria. “We know we’ll be fit and we’ll know that we’ve done something.”

While many schools have tended to cream off their brightest and best to take part in the award, being disaffected, chronically absent or barely literate makes you an ideal candidate at Ashford. Some students predicted to get grade Fs in GCSEs are on track to get the gold award.

History teacher Nick Charalambous, who runs the award here, believes this is the way it should be. “I made a point that I would not become involved if it was exclusive,” says the intense, dark-eyed teacher. “Some schools limit the number of pupils who can do it; others want an application form, which puts off youngsters demotivated by writing. If they’re willing to do it, and it has a value to them, why limit it? And if you have to limit it, it should be for those who need it most.”

Mr Charalambous takes a pro-active approach to recruitment along the corridors of Ashford High. “We target and we hound,” he says. Sixty per cent of pupils in Years 9, 10 and 11 are involved, and signing up is a condition of entrance for pupils who join the school having been excluded from others. For the few who drop out, the door remains open.

The result is that on Thursday evenings the school hall throngs with up to 300 pupils pursuing their bronze, silver and gold medals. They are doing everything from circus skills to car maintenance and cactus culture. Some 87 per cent complete the level they start, and 15 per cent continue to gold level.

Headteacher Vanda Tillotson - brought in four years ago to revive the then-failing school - gives the award scheme a large part of the credit for all-round improvements. “We believed pupils who were self-confident and gained high self-esteem could raise their academic achievement in the classroom,” she says.

Although Ashford High is still unusual, the award scheme managers hope increasingly to reach children other than the high-achieving sporty types in independent schools with whom it has traditionally been associated. They commissioned a study by the National Foundation for Educational Research (NFER) to find out what people thought about them, and how the 43-year-old Award might “ensure its continued appeal and relevance for young people well into the next century”. Respondents didn’t mince their words, suggesting among other things that Prince William would make a more attractive figurehead than his grandfather and that the award’s Establishment roots were off-putting. “I think of royalty... the upper classes... boring people.”

If they really want to reach marginalised young people of all races and religions in the inner cities, you might wonder if appointing a vice-admiral (with Ampleforth, Dartmouth and Trinity College, Cambridge, on his cv) as the new chief executive last year was the way to go. But after 35 years in the Navy, Michael Gretton says he has a good understanding of young people. “I commanded a ship - HMS Invincible, you might have heard of it - where I had a ship’s company of 1,100, with an average age of 19. I love people, and adore the young.”

He says the award has always used the patronage of royals, the upper classes and top brass of the Forces to reach out to the dispossessed. “It’s inherent in the programme. When it was started, the objectives were very much to help those people who were less motivated. But then it got taken up in solid schools with supportive parents, motivated young people and very good teachers. Now in a sense we’re going back to our origins.”

Annual dinners at St James’s Palace oil the corporate fundraising wheels rather well, and for every republican teacher or youth worker turned off by the royal connection, there are apparently plenty of young people quite chuffed by it. “It’s really about companionship, saying you’re as good as anyone else and you’re going to get a certificate signed by the Queen’s husband,” says Bob Le Vaillant, who has brought D of E to Tower Hamlets in London’s East End.

Michael Gretton mentions with particular pride the scheme in Tower Hamlets - a borough distinguished until recently by bumping along the bottom of educational league tables and the top of poverty ones - where young Bengali men and women are joining up, as are pupils from EBD special schools, under the auspices of Stepney Children’s Fund.

He also points out that in Wales the award has been enthusiastically taken up by the prison service and probation and pupil referral units, and admits to talking more frequently to the Home Office than to the Department for Education and Employment; the Government has obviously recognised the scheme’s potential with the non-clubbable.

Despite the popular image of the award’s founder (as gifted with little tact or emotional awareness, let’s say) the scheme is concerned with individual development on individual terms, with the journey rather than the arrival, and it is this that makes it highly transferable. “It’s not about running 100 yards in 100 seconds,” says Michael Gretton. “It’s about doing something rather better, having persisted at it, than when you started.”

In other words, a good antidote to educational failure. “It compensates for what some children are not going to get from the national curriculum,” says Bob Le Vaillant, of Stepney Children’s Fund. “Lots of young people are failing education or being failed by education and we believe that having a nationally-accredited certificate on your cv might just get you the interview.”

In what may be music to the Duke’s ears, Bob Le Vaillant says that many of the original elements of the scheme hold good. “Our children seem to like sitting round a camp fire toasting a sausage. And these are kids who often wouldn’t walk between bus stops, so there must be something that motivates them to do a 15-mile hike.”

It’s not always easy to arrange, though. Getting young Bengali women from Brick Lane and Spitalfields down to Lord Northbourne’s 2,500-acre estate in Kent for summer camps took three years of negotiations with community leaders, and required extra protection, all-female leadership and facilities for washing, praying and Halal food. National Foundation for Educational Research studies also highlight significant barriers to take-up by all young people. Cost is a key one. Bob Le Vaillant estimates that it costs pound;400 to put a young person through the bronze award, if - like most Tower Hamlets teenagers - they don’t already have climbing boots, waterproofs, rucksacks and the rest of the kit. “If they want to make a major breakthrough with poor children they need some form of bursary back-up,” he says.

Volunteer time is another problem. Nick Charalambous puts in 30 hours a month for the scheme at Ashford High and says that if he had a family of his own he probably couldn’t do it.

As it is, he finds that working with children who live next to the world’s busiest airport but rarely go beyond a three-mile radius is its own reward. Ben, hair-gelled and smelling of Lynx and chewing gum, recalls his last Duke of Edinburgh expedition. “We lost the map and everything was sopping wet. We were lost for two hours in the wood and we were the last people in the camp and had to pitch our tent in front of stinging nettles. It was a laugh.”

YOU CAN DO IT

* The Duke of Edinburgh’s Award is for young people aged 14-25.

* There are three levels of Award: bronze, silver and gold. Each has an increasing degree of commitment.

* To gain any one of these levels, each young entrant must complete four sections: Expeditions, Skills, Physical Recreation and Service.

* For gold, participants must also complete a residential project, away from home for at least five days.

* For more information and details of local ‘operating authorities’, contact The Duke of Edinburgh’s Award, Gulliver House, Madeira Walk, Windsor, Berkshire SL4 1EU. Tel: 01753 810768.