There I was, moving methodically up and down my lane, listening to the hubbub of the municipal swimming pool on a Sunday afternoon. In the part of London where I swim, voices come in many tongues, but this time one language rang out above all others: the language of disorder.
From the racket they were making, you'd have thought there was a whole gang of them. But when I stopped for a brief rest I could see that the troublemakers numbered only four. And they couldn't have been older than 12 or 13.
Tired of leaping off the side and on to the heads of younger children, they were currently engaged in a freestyle race, ploughing through anyone foolish enough to be in their way. When this began to pall, they took up position in the centre of the pool and started a ferocious splashing match.
Most of the other swimmers - families out for their weekly recreation - cowered in the shallow end, looking to the lifeguards for support. One, a girl hardly older than the miscreants themselves, approached and was duly ignored. Two or three others joined her, none with any clue how to handle the situation.
Eventually, after several blows of the whistle, the boys waded over to the side. I couldn't hear the exchange, but their body language suggested they would carry on doing whatever they wanted. An older attendant (probably all of 21) arrived. He wandered around the edges of the pool trying to engage the kids in conversation. This seemed only to incense them. Who was he to tell them what to do?
From then on, one thing was clear: the boys were in charge. The ground had been ceded to them and everybody knew it.
I went back to my metronomic progress up and down the lane. It was an interesting situation for a teacher: being faced with misbehaving children but having no authority at all. Every time my head came out of the water, the effing and blinding in the air told me they were still at it. Eventually, when most of the other swimmers had quit the pool and there was no one left to torment, they moved noisily off to the showers.
By the time I got out, they had disappeared into the changing rooms. It didn't seem to have occurred to the attendants that they might need to keep an eye on them in there as well. But the screams of delight and the sound of furniture being dragged around suggested that it probably should have.
When I went through to change, there was no sign of the feral youths, just a few attendants surveying the aftermath. "Is this what I think it is?" one young man asked his friend. Together they eyed a pool of yellow liquid in the plastic baby changer.
I passed the four boys as I drove home. On their faces were looks of quiet satisfaction. They had come, they had seen and they had done exactly as they pleased. But I couldn't help thinking that the next time I saw some of those faces it would be on Crimewatch. And there was nothing I could do about it.
Stephen Jones is a lecturer at a further education college in London.