On 18 September, an exhibition opens in London unlike any show I have ever seen. Timeless, classless and utterly indifferent to artistic fashion, the exhibits seem to have no unifying theme. Yet despite their diversity, they do have something in common: they are all made by prisoners, and they are all winners of the Koestler Awards.
Arthur Koestler drafted Darkness at Noon under sentence of death during the Spanish civil war. By the time it was published, during the Second World War, he had been interned in Pentonville. After the war, he campaigned against injustices, from capital punishment to Soviet communism - and in 1960 he came up with the idea for an annual art competition for prisoners. It won the approval of the Prison Commission (no small achievement, in a year when three men were hanged in Britain, including an 18-year-old) and the active support of the Tory home secretary Rab Butler. By 1962, his project was up and running. Its chairmen have included Sir Hugh Casson, David Astor and, currently, the former chief inspector of prisons, Sir Stephen Tumim.
Today, the Koestler Award Scheme embraces more than 60 categories - from playwriting and hairdressing to dressmaking and computer graphics - yet fine art remains at the heart of the programme, and its annual highlight is this public display. There are more than a thousand prizes (some sponsored by artists, such as Maggi Hambling and Brian Eno) and all of the artworks are for sale. It's a free market - not just philanthropy - and that is a big part of its appeal. Every year, thousands of inmates submit work from every prison, young offender institution, secure unit and high-security psychiatric hospital in the country (135 altogether), and the winning entries are hung together.
Aptly, this nationwide enterprise is run from a big old Victorian house right beside Wormwood Scrubs (just around the corner from BBC White City). Originally the governor's residence, it was subsequently a lifers' hostel, and it still feels like a halfway house - just outside the prison walls, but within the prison gates. Once inside, however, sculpture and ceramics line the shelves, like lots awaiting auction. Upstairs, there are so many canvases stacked up against the wall that you have to walk on tiptoe. Surreal and escapist art seems especially popular among prisoners; the therapeutic work produced in prison hospitals is often more expressionistic. Yet what really distinguishes the best work is its individuality. The Royal Academy "Summer Exhibition" has never been like this - and I doubt it ever will be.
What makes this art so fresh is its untaught candour. Not that it is unsophisticated. Many pieces demonstrate the sort of fluent draughtsmanship that more fashion-conscious artists tend to shy away from. It wasn't made to impress a dealer or a curator. It doesn't belong to any genre. It owes no allegiance to any school. Some of it comes from prison art classes, but much of it was made in even greater isolation - often in complete seclusion, alone behind a cell door. Hardly any inmates are able to attend this show. Most of them only ever see their own work, and will only ever see it again if it is returned to them unsold (though newly framed).
The art that Koestler's scheme champions has several benefits. Most simply, a prisoner busy making art is not busy making trouble. Illiteracy is no bar to success in painting. "The case for art in prisons is not theoretical - it is practical and pragmatic," writes the film-maker and criminologist Roger Graef. "In place of passive formal classes, the arts provide the first forms of learning." Art, like crime, can be disruptive and subversive. However, unlike crime, it is also a way to win the approval and acceptance of the establishment. Koestler's awards are often the first prizes these prisoners have ever won.
A Koestler award can lead to a career as an artist. Peter Cameron, the laconic, erudite Scouser who showed me these artworks, started painting in prison while serving a sentence for smuggling marijuana. His first picture was of two chimpanzees in prison uniform. Another prisoner bought it from him - for half an ounce of tobacco. He'd never painted before. He entered the Koestler and came top in the watercolour category. He won £100 in prize money, and sold the painting for £200. "I could buy my old lady a birthday present," he says, "which is something you can't do on the wages in prison."
As well as earning him an income, painting gave Cameron a sense of control over his surroundings. Grim old prison buildings, such as Durham, became favoured subjects for his art. "It's awe-inspiring," he says. "You can just sit there and imagine who's been here before you." He won the Koestler three years running and even sold a painting to Sir Stephen Tumim. Today, he combines painting with a job as joint manager of the Koestler Trust.
News of the Koestler has spread far. Cameron has been sent prison pictures from Spain and Egypt. One was even sent in by an American on death row, to try to help raise funds for his appeal. Cameron would like to see the scheme become more international, but it all costs money. The Home Office gives the trust use of the old governor's house, but most of the funds to run the scheme come from charitable contributions. Last year, Antony Gormley and other artists donated works for an auction in the Wormwood Scrubs chapel. The sale raised more than £50,000.
"Arthur Koestler's vision was far ahead of its time," writes Tessa Jowell, the Culture Secretary. "Creative activity not only enables prisoners to create art of the highest quality, but also provides a strong basis for critical self-reflection." Or, as Cameron puts it, "Most of the time, people have been told they're crap at everything: this is someone who'll tell you that you're good at something."
Above all, this extraordinary collection shows that making art is a basic human need. We all made art as children, and when we are thrown back on our own resources, we feel compelled to make it once more. When Lord Leighton was a boy, he was once punished for some childish misdemeanour by being locked up in his bedroom. "I don't care," yelled the great Victorian painter through the keyhole. "I have a pencil."
Back outside, a bust of Elizabeth Fry watches over the entrance. "Punishment is not for revenge," said the grandmother of prison reform, "but to lessen crime and reform the criminal." I don't know what she'd make of Wormwood Scrubs, but I think she would approve of Arthur Koestler's awards.
The "Koestler Exhibition 2003" is at St Mary Abbots Hall, Vicarage Gate, London W8 (020 8868 4044) from 19 September to 5 October. Admission free