It looks like a scene from one of those TV shows where men construct improbable machines using bits and pieces from the local recycling centre.

There are wires, plugs and all manner of electronic components, together with enough mechanical odds and ends to keep Heath Robinson happy for weeks. And at the centre of it all is Jamie Woods, a 15-year-old with a mobile phone and a clear idea of what he needs.

What he needs now is a new set of micro switches for his electric wheelchair. Not because he wants to keep up with the latest fashion, but because the existing switches are so big that he occasionally knocks them by mistake, with alarming consequences.

Fortunately, Jamie is in exactly the right place. Treloar School, in Froyle, near the Hampshire market town of Alton, employs eight rehabilitation engineers, with workshops on the premises. If something needs fixing, adapting, or even making from scratch, it can be done without appointments and with a minimum of fuss. Most important, it can be done quickly. And for all too many of the students here, time is of the essence.

Jamie has muscular dystrophy, a progressive disease which destroys the muscles. In the summer, he had a major operation to straighten his back by fusing the vertebrae. But, just weeks later, here he is, attending lessons and mixing with his mates.

Such a thing could only happen at a school such as Treloar’s, which has 24-hour nursing and medical care and where all kinds of support, from physiotherapy to speech and language therapy, can be brought to the dining hall, the bedroom and - most important given the school’s emphasis on offering the national curriculum - into the classroom itself.

Even among special schools, Treloar’s is clearly rather special. It was founded by Sir William Purdie Treloar, a businessman who, prior to becoming Lord Mayor of London in 1906, launched the “Lord Mayor’s Little Cripple Fund” in order to build a hospital and college for some, at least, of the city’s physically disabled children. Within two years, the fund, which benefited from royal patronage, had raised pound;60,000, around pound;4 million in today’s money. And in 1908, Sir William and his wife, Annie, welcomed the first children to Alton.

In Sir William’s day, the primary causes of physical disability in childhood were poliomyelitis and non-pulmonary tuberculosis. By contrast, most of today’s 135 students have cerebral palsy, a condition common among the increasing number of children who, thanks to advances in the very medical science that all but eradicated polio and TB, are now able to survive premature birth.

But one thing that has not changed since Edwardian times is the support which Treloar’s receives from the City of London and its guilds and livery companies. The annual visit of the serving lord mayor has become a prized tradition, and one which provides a useful impetus to the fundraising on which the Treloar charitable trust still depends.

In the 2004 government performance tables Treloar’s was among the top 5 per cent of schools nationally for “added value”. But providing round-the-clock care as well as an education clearly does not come cheap, which is why parents can find it difficult convincing a local authority that their child should attend Treloar’s as a weekly or termly boarder.

“The first reaction of many LEAs,” says headteacher Neil Clark, “is to say that local provision is better, even if it is 40 miles away from a child’s home. At a tribunal, it’s argued that the local special school costs the LEA nothing because they’ve got to keep it open anyway, where a non-maintained special school like ours may cost pound;40,000 a year.

“But often, the reasons parents are seeking a residential place are social.

They need respite, and they need somebody to look after their kids for 36 weeks in the year.”

Having taught in comprehensive schools, he is aware that many children with disabilities can flourish in a mainstream setting. But as someone who, 16 years ago, was briefly torn between accepting a deputy headship at the Royal Ballet School in Richmond or the post at Treloar’s, he feels strongly that parents and children should have that option.

“If a kid’s got dancing talent, nobody questions that they should go to the Royal Ballet School, and that it should be paid for at the public expense.

But if you’ve got a child with special needs and you say, ‘I want them to go to a specialist place called Treloar’s because they’ve got the equivalent of the choreographers and the physios and the equipment’, parents are often made to feel guilty for even contemplating that.”

It’s a view that is echoed by another head, at another Treloar’s, just three miles up the road in Alton town. For the charity which Sir William launched a century ago maintains two educational establishments - Treloar School, which takes children aged five to 16, and Treloar College, which is the only beacon FE college of its type in the UK.

Here, principal Graham Jowett and his staff pride themselves on giving disabled students up to the age of 22 a special kind of further education; one which will equip them, not only with work skills, but with the confidence and assertiveness (Dr Jowett calls it “bolshiness”) they will need in order to fight for their rights in the outside world.

“When they come to us,” he says, “I tell the students that the benefit of being here is that we can deal with most of the practical disability issues on site and give them the space to mature emotionally and test out their adult identity.”

Many have been in mainstream schools, the “lower” Treloar’s accounting for only about a third of the college’s intake, and all will have made a positive decision to come here because “they were getting fed up with being the centre of attention”, as Dr Jowett puts it.

“They have always had special arrangements made for them - a support assistant opening doors and carrying their laptop - and it’s a relief when they come here. They do what young people do. They fall in and out of love with amazing regularity. And when they get a bit older, they start to use local hostelries and sometimes misjudge their alcohol intake.”

It might not be exactly what the lord mayor had in mind all those years ago. But somehow, you can’t help thinking that the man who wanted disabled children “not to whine over their physical defects but to face the battle of life with confidence and courage” might just approve.

Treloar’s needs to raise pound;2 million each year, just to stand still.

To mark its centenary, it is doubling that target for three consecutive years, in order to provide funds for additional facilities and outreach projects. To this end, Treloar’s has been named as the beneficiary of the new Lord Mayor’s Appeal, and its float will have pride of place in the Lord Mayor’s Show tomorrow

* ‘I’ve never seen anything like it’

If it were not for the round-the-clock medical care that Treloar’s can provide, 13-year-old Lauren Scott could not go to school.

Lauren has a rare muscle wasting disease which means she requires up to four hours of skilled medical attention each day, and long periods of rest.

Yet at Treloar’s, she is able to join in lessons every morning, and have lunch with her friends, even though her food must be taken through a tube.

“The individual education plans are just that: individual,” says Lauren’s mother, Julie Scott. “I’ve never seen anything like it before. Normally, disabled children have to choose whether they’re at physio or in the lesson, but at Treloar’s they will actually be doing their physio in the lesson, and they could take the class into the medical centre if she was having a weaker day.”

Lauren spends weekends and holidays at home in Croydon, attending the school as a weekly boarder. “It’s better for her sister and brother,” says her mother. “Because we’ve got four days in the week where we have time to do the normal things, the weekends can be more devoted to Lauren.”