For 280 hours - five hours a day, seven days a week, for eight weeks - Ball, a pupil at the school, had laboured on his hands and knees in the art department, painting, in the mode of a right-way-up Michelangelo, something whose entirety he could not see. His mission was to bring to Eton a contemporary Christ with whom the boys could identify. "I wanted to make people really think about the whole significance behind it [the Crucifixion]..." he wrote in a pamphlet on offer at the chapel's entrance. "It is something I feel strongly about."
When the work was finally hung and Ball saw it for the first time, he must have realised that he had achieved his objective. Aside from the sheer scale of the tennis-court-sized work, the whole exudes a truly disturbing sense of youth in its greatest bloom, tragically on the brink of extermination. It is a picture of a torso - an adolescent torso - rippling with young muscles. The beardless head is thrown back in such a painfully contorted way that the onlooker wants to clasp at his or her own throat in sympathy. The painting has drawn viewers from across the country, including Princess Margaret and the Queen Mother (who wrote an effusive letter to the school's provost, saying how much it had moved her).
To an outsider, much of the painting's force lies in the sheer unorthodoxy of Eton allowing it to hang in such a prominent position. "I was amazed the school let me do it," confesses Ball, "and my greatest fear was that, when they saw it, the boys and masters - particularly the masters - might find it distasteful. It is, after all, rather controversial."
The controversial aspect of the painting lies in the modernisation of Christ. Ball has omitted all the traditional symbols of the Crucifixion. There is no crown of thorns, no nails, no blood and no beard. "The feelings of pain and power are best descried by the muscles, ribs and tension in the throat and shoulders," Ball explains. "Everything else is a clich and unnecessary."
Far from provoking complaints, the painting made some boys cry. And if any of the masters had reservations, a sermon - "The Crucifixion with Reference to Adam Ball's Painting" - preached by John Witheridge, the school chaplain, must surely have converted them. It focused on three main themes: the humanity of Christ, the suffering of Christ and a contemporary Christ. "The Christian Church", Mr Witheridge said, "is not a fan club for a dead hero."
The strangest thing about Adam Ball face to face is that he is neither a Bible-basher nor a conventional artist. (I'd almost expected wild hair, nicotine breath, even an earring.) Instead, he is a rather diminutive chappy with a wide, endearing grin wearing a Marks & Spencer jumper, corduroys and brogues. "My mother says I'll probably be painting in pinstripes when I'm 50," he laughs. In the shorter term, Ball has a place at the Byam Shaw School of Art in London for September, and hopes to finish his studies at Ruskin College, Oxford.
Ball is concerned that the painting, which Eton has just taken down, should go to the most appropriate home. Fortunately, at least one offer has been made, from St Bartholomew's in Brighton, a suitably vast church. "I would just like people to be able see it," says Ball, adding with a sudden grin, "Not, though, because I'm out to convert people." He pauses and is serious for a moment. "At the end of the day, I'm an artist, not a bishop.''