The bathroom was in the basement of the old Student Union building: a canker sore of grubby floors and walls buried under a Victorian gothic shell. You got there by going down a staircase by the pinball machines, and then going through a battered door. But when you opened the door, the first thing that hit you was the reek of ammonia and strong bleach. Overhead, a pair of fluorescent lights sputtered and hummed, illuminating the bathroom in their harsh light.

On the wall opposite the door was a single, long tiled trough, its enamelled surface streaked by decades of water and young men's urine. Next to it was a row of grimy sinks, fastened to the wall by rust-encrusted bolts and pipes. Between these and the door was a blue roller towel that was damp and smelled of mould. Last of all, there were the cubicles.

There were three cubicles. Each one concealed a porcelain throne with a wooden seat, the surface of which had been polished by years of students sitting on it. The bowls of the toilets were connected to overhead cisterns, painted with red lead. The manufacturer's name stood proud from the metalwork. A metal chain dangled from a lever, and could be used to actuate the flushing mechanism and send water into the waiting bowl. But these were never used, except by the cleaners. Instead, people came here to think and to write.

The walls of the cubicles were covered in graffiti. These were not the desperate cries for recognition that were found elsewhere around the university campus. No. The graffiti found here were more deliberate. People came down here to pour their hearts out, to write philosophical treatises and to unburden their souls of their sins and transgressions - all in various shades of ink on the toilet walls. Every so often, some anonymous drone in the university bureaucracy would be tasked to erase these writings and repaint the cubicle walls in a sickly blue. For a while - a few days, a fortnight at most - the newly-painted walls would stand virgin and inviolate. Then the words would appear again.

Those of us who came here to write were unknown, even to each other. But, somehow, we had formed a bond. I thought of us as some kind of brotherhood: an invisible college. Together, we policed what was written on the walls, deciding what was acceptable and what was not. We did not tolerate simple obscenities, but we did not consider anything sacred. Even the most profane prose would be allowed provided we thought it had merit. None of our work was signed, but we came to know each other from so many other signs. The colour of ink, the size of pen, the style of handwriting. Crude block capitals were for hoi polloi.

Some years after graduating, I returned to my seat of learning. It was an open day, where prospective students came to be sold a vision of their future. I, along with the other parents, was being shown around the Student Union by some thin-faced, earnest youth, He led us through the building, proudly declaring how it had been renovated by the university authorities. He showed us the new atrium and dining rooms, the student bar and the great meeting hall. Halfway through the tour, I asked our guide about the sanitary facilities, then excused myself.

Downstairs, the air was filled with a suffocating perfume. The walls and ceiling had been repainted in bright colours, and artful lighting cast a blue, antiseptic sheen over everything. The old trough urinal had been removed, replaced with three discretely-screened bays. The battered wooden cubicles had been removed. In their places were a row of purpose-built stalls with floor-to-ceiling walls. I went into one and closed the door.

I looked around. The walls were clean, sterile. On the back of the door was a framed notice advertising a counselling service for "troubled students". A sudden urge took me. I fumbled in my jacket pocket and pulled out a black Sharpie pen. Then, on the door, I wrote in fine, black letters: "And this, too, shall pass away."