Brushing aside assumptions about what makes an artist

He looks every inch the tortured artist as he ponders an evolving masterpiece on his desk, seemingly oblivious to the chorus of slapping paintbrushes resonating all around him.

The art class is in full flow; three frames of perspex "canvases" are being splattered with red paint and fingers are carving intricate translucent designs in the mass of colour.

Though the air is frenetic, Liam sits studiously and muffled-eared, blotting out the commotion.

Aged just 16 he is already an artist with a talent for abstract expressionism, earning praise at exhibitions across the city and scooping top prize in an Edinburgh and Lothians regional poster contest for the Edinburgh Festival Fringe. It is currently mounted at the city's Museum of Childhood.

As a pupil at St Crispin's School the teenager is in fine company, with the work of three classmates adorning the National Galleries of Scotland following similar success in creative competitions.

The school has been making waves in the art world for the last five years and its latest exhibition, On The Move at Gallery on the Corner, is due to close tomorrow at 4pm.

But it is clear today, with new guests flashing cameras and scribbling into notepads, Liam's creative juices are diluted by disruption.

Like his 60 schoolmates, routine is sacrosanct. Even small deviations from the daily timetable can stoke anxiety and challenging behaviour.

Arriving slightly late, the four artistic prodigies we have come to meet should already be settling into their next class and staff are wary not to stray too far off schedule.

Each pupil at St Crispin's finds comfort in regularity as all suffer varying degrees of severe mental disabilities, often characterised by limited speech, poor motor skills and "challenging" behaviour.

At least 75 per cent of those are living with autism.

"The rest of the world is such a scary place for them. Any of us trying to think or speak in a foreign language will know how frustrating that can be but that is what these kids have to go through every day," explains headteacher Ruth Hendery.

"We live in a world governed by words. Everywhere you go depends on being able to read or hear or understand words. For most of our children this isn't possible."

As a spectrum condition, there is no catch-all definition for autism nor one-size-fits-all therapy.

Some people with autism are able to live relatively independent lives while others may have accompanying learning disabilities and require lifelong specialist support.

Little wonder it is dubbed the "hidden disability".

Some may not like colours or bright lights while others may like them a lot.Some may be tactile while others spurn physical contact.

A common symptom of people with autism is trying to understand the world in which they live.

The ability to communicate, whether emotionally or verbally, can be stifled - sometimes severely. The school subscribes to a principle of "total communication": using images, gestures, symbols and rudimentary sign language - alongside the spoken word - in dialogue with the children.

However, despite the difficulties in pigeon-holing, almost without exception, fidelity to routine is one unifying feature of the illness.

And school staff go to extraordinary lengths to ensure ease of transition to timetable changes or new and unfamiliar surroundings.

Heather Lucchesi is the school art teacher whose indomitable patience and compassion has been a catalyst for the pupils' artistic progression in recent years. One example of her "beyond the call of duty" spirit sticks out in the mind.

Ahead of a school visit to the National Galleries of Scotland, she mapped out each leg of the journey in photographs which she showed the pupils before they made the trip themselves.

The work of her students looks perfectly at home alongside that of children from "mainstream" schools.

In a brief interlude from lessons she explains how, for many pupils, art has become a visual platform to express themselves and communicate.

"Sometimes they can arrive here quite agitated and leave in a better frame of mind after doing some art," she says.

"You can get a feeling of calm being here but if you don't explain that this activity has a definite end it can stop them from even trying.

"But their work takes as long as it takes them.

"We don't have artists worried about if it looks the way it should and they don't have a teacher telling you what it should look like.

"I think that there's not many opportunities for these children to shine through to show what they can do."

But this is a case where they can. There seems to be something about the work, a real energy that appeals to people.

"It's not just the people who know the children who can see this, it can be complete outsiders who really do engage with the work.

"Many people do say it's just as good as other work they've seen in galleries."

Later Ms Hendery adds: "When you see parents admiring the work it's very special because for nearly all these children they don't produce much written or oral work so their art work is the most tangible form of their progress."They may be at an early level for many subjects but their artwork can easily sit beside professional artists or mainstream pupils."

Paul Penrice, an arts development worker at Gallery on the Corner which has exhibited St Crispin's for the last three weeks, revealed that 41 of 52 works mounted had been sold.

"The exhibition has appeared to intrigue viewers at the gallery because of the high standard and the diversity of the work," he says.

"It's fair to say that the artworks aren't perhaps the kind you might normally associate with that of children, the work seems more mature and more considered, which has undoubtedly made the show so successful both commercially and in terms of artistic expression."