At 10 past seven on the evening of February 11 1873, two men were arrested while having sex in the men's public lavatory on St Christopher's Place, just round the back of Oxford Street. In the London of the time, 20 years before the Wilde trial, such arrests were not unusual, but this one featured a highly unusual combination of culprits. One of them was an illiterate, 60-year-old stableman (Mr George Roberts), while the other was the 33-year-old youngest son of a respectable East End Jewish family, a rising star of the London art scene. At the time of his arrest, Simeon Solomon was a fashionable young watercolourist, engraver and oil painter, who, on the strength of his early work, had been lionised by Rossetti, Swinburne and Pater; his drawings had been hailed by no less than Edward Burne-Jones as the next big thing of the pre-Raphaelite movement.
The two men were treated very differently by the courts - and have been treated very differently by history. George Roberts was sentenced to 18 months' hard labour (the same sentence that 20 years later nearly killed Wilde, a considerably younger man), and, once sentenced, disappears from the records. Solomon, meanwhile, got off with a £100 fine, and had the bad manners to live on, unrepentant, into the 20th century.
Who was this man? Well, 1873 was not the first time that Solomon had misbehaved in public. Already a heavy drinker, he specialised in dressing up in vaguely eastern robes and flaunting his equally flowing red hair - this at a time when to risk appearing either too Jewish or too effeminate was considered unwise even at the most advanced of art world parties, and to be both at the same time, unheard-of.
If his misdemeanours had been merely sartorial or sexual, Solomon would probably be nothing more than an intriguing art-historical footnote. It is the way that he carried his transgressions from his life into his art that makes him a man worth not just commemorating, but celebrating. All his pre-Raphaelite peers indulged in variations on non-specific sexual moodiness - all those heavy-lipped and -lidded beauties that still make Burne-Jones and Rossetti such popular choices at the postcard desk. Solomon took this costume drama of anguished ambiguity and made it luridly specific. His early oils feature a succession of handsome, androgynous boys variously posed as rabbis, gods, acolytes or angels, whose private thoughts are quite clearly not on religion. For close friends and colleagues, he produced private small-scale drawings in which the veiled gazes of masculine desire are accompanied by actual gestures of tenderness - still furtive, and mostly unhappy, but none the less there.
Meanwhile, in his public works, Solomon's images of love came dangerously close to pronouncing a name that this country's art still hadn't dared speak. In the mid-1860s he created two very different pictures of the lust that would later lead to his arrest. One is his best-known oil, a young man's exercise in high kitsch entitled Love in Autumn, featuring a lightly draped, flame-haired angel blown into exile across a distressed Mediterranean landscape by the chill winds of English social disapproval. This iconic image is to painting what Lord Alfred Douglas's famous sonnet was later to be to fin-de-siècle literature: a declaration of a kind of sexual desire that was - but would shortly no longer be - stifled.
In the same year, Solomon also created the image that is my personal favourite; it is perhaps the most daring, and certainly the least expected. Commissioned in 1866 by the popular illustrated magazine The Leisure Hour to make a series of six picturesque engravings showing the religious ceremonies of the London Jewish community, he produced a drawing entitled The Marriage Ceremony, which shows the bride and groom with their faces shaded by the traditional Jewish wedding canopy. At the very edges of the picture, holding the poles that support the canopy, are two men who seem to be paying very little attention to the ceremony taking place in its centre. Both wear white gloves and top hats; one is a schoolboy, one a handsomely moustachioed man-about-town. The pouting prettiness of the boy is entirely predictable, but the tender seriousness with which his would-be suitor gazes at him is without precedent.
What would the painter who created such a startling pair of images have done if his career hadn't been cut short by an arrest? The question is tempting, but unanswerable. Meanwhile, there is a more interesting one to be asked: was the arrest in fact Solomon's making rather than his undoing?
After the arrest, it quickly became apparent that a conventional career was impossible; famous friends dropped him, public commissions were unknown and even private commissions understandably scarce. Remarkably, Solomon kept working in the face of this ostracism. Occasionally he produced full-scale finished works for the few patrons who stood by him; but most often, unable to afford canvas and oils, he drew in chalk and charcoal, on paper and salvaged cardboard. He even, on occasion, worked as a pavement artist outside the Brompton Oratory.
In these late drawings, the besetting sin of British pre-Raphaelitism - its well-upholstered sentimentality - is of necessity burnt away. All that is left of his earlier repertoire of androgynous posturing is a handful of simple, dream-like images, which he drew again and again: most commonly, either a pair of faces, gazing either at each other, or a single visage gazing deep inside itself. In these late works, he found his true subject - the introspective mind. As he repeats and refines the imaginary features of his subjects, in increasingly summary strokes, sometimes made shaky by illness or alcohol, something else emerges besides beauty. What matters here is scrutiny; the inward gaze of conscience. It is as if, by tracing the same features over and over again, Solomon thought he might uncover the dreams that forever hover just behind their lowered eyelids. By the end, the faces are not just androgynous, they are sexless, impersonal, living in a lonely realm of shame and hunger, of desire and dreams.
Perhaps, far from destroying him, exile from polite society forced Solomon to create the most moving - and perhaps the most truly beautiful - work of his strange and troubled life. Looking at these obsessively imagined faces 100 years later, it is hard not to think that their hungers remain unappeased, their dreams still unrealised.
For all the years of poverty in which he was producing these remarkable images, Solomon manifested no trace of apology for his so-called crime. Destitute and alcoholic, he refused the support of his family, and was sometimes reduced to selling matches on the Mile End Road to survive. He spent the last 20 years of his life living in the St Giles workhouse - an address he favoured, he once told a journalist, because it was "so central". The transgressive spirit that 30 years earlier had made him risk his reputation because he fancied a stableman called George was clearly still alive and kicking.
A century after his death, Solomon now seems more than ever a visionary, an artist who set an agenda. He drew things others hardly dared envisage; he made the act of making an image personal, and dangerous, and honest.
· Love Revealed: Simeon Solomon and the Pre-Raphaelites is at the Birmingham Museum and Art Gallery, Birmingham, until January 15. Details: 0121-303 1966.
· Neil Bartlett's performance piece about the life and work of Simeon Solomon, A Vision of Love Revealed in Sleep, has just been published in the anthology Solo Voices (Oberon Books).
