When I was 12, I had my first experience of the effectiveness of 'neighbourhood watch'. Three boys who felt I was trespassing on their territory decided to beat me up. When a passing adult intervened, the boys agreed that, no, three on to one wasn't fair, and so after telling me to run on home my rescuer rode off into the sunset. The three boys then ran after me and continued with the beating.

At least they had the decency to wait until the man had gone. Now, it seems, there are no guarantees.

Out running recently, I saw a paperboy being given a good kicking by another, bigger boy. Reluctantly, I detoured to break it up. I didn't expect it to take long. They were only kids, after all.

Fifteen minutes later I was still there. The paperboy, who was white, was hiding behind my back while the other boy, who was black, did his best to continue kicking him. The paperboy, he claimed, had called him a black bastard, owed him money, and had arranged to have him beaten up by a gang of his friends. Needless to say, the paperboy, cowering tearfully behind me, denied all of this. The other boy was simply bullying him, he said.

I was beginning to wish I had chosen another route to run on. I had no idea who was telling the truth, and while I didn't want to protect a budding racist, I could hardly walk away and let the slaughter continue. I decided to try reason. 'Look,' I said to the black youth, aware of sounding like a cliched, ineffectual, white adult, 'if he called you that he shouldn't have. But hey, he's in tears, he's had enough, OK?'

It wasn't. 'I'm going to kill him,' was the response, followed by another flurry of arms and legs.

I was running out of ideas. If the fact that I was an adult wasn't deterrent enough, what could I do? Finally, there was a breakthrough. The black youth calmed down and agreed to end hostilities. As a sign of good intent, he even offered to stay with me while his white opponent took himself to a safe haven. But the paperboy was still suspicious. 'He'll just run away from you and catch me,' he fretted. 'I'm a runner,' I assured him, pompously. 'He won't'

Of course, he did.

Waiting until the paperboy was 50 yards away and I was lulled into a false sense of security, he suddenly sprinted off, mid-sentence. Hearing him coming, the paperboy set off like a bat out of hell, and I ran after them both, all too aware that the sight of a man in skimpy running shorts chasing two schoolboys down the street could easily be misinterpreted. By the time I caught up, my temper was frazzled. I began herding them towards a telephone booth, the paperboy once more cowering behind me while the other did his best to kick him. To hell with reason. This was a job for the professionals. 'I'm calling the police,' I said.

It did the trick. Neither boy seemed keen on the involvelment of proper, uniformed authority, and a truce was quickly agreed on. With the paperboy still peering out from behind me, the other boy disappeared into the distance. Even then the paperboy was convinced it was another ploy, and I soon found myself accompanying him on his paper round as a minder. Luckily, I came to my senses before he could persuade me to deliver the newspapers for him, and escorted him back to the newsagent's instead.

If I expected a tidy ending I was disappointed. Neither the paperboy nor the newsagent said so much as thank you. I could not even congratulate myself on doing a good turn because I was still by no means sure which boy had been telling the truth. And I had probably only delayed the inevitable, anyway.

As I left the shop, with the paperboy and his boss discussing newspaper delivery, I passed the other boy in the doorway. Ignoring me, he marched towards them with a determined look on his face.

I considered going back inside, but didn't. I felt stupid and ineffectual enough as it was. I resumed my run, telling myself it was in the hands of another grown-up now. Let him see if he could make a better job of it.

I had been a 'good citizen' and found that good intentions aren't always enough. And I had literally only run into trouble; I hadn't gone out looking for it. That's the job of the police.

Isn't it?