Fagin lives on in London

WHEN I left the Knightsbridge branch of Lloyds, having just withdrawn pounds 50, I felt a tiny child bump against me. Or rather, he bumped against the shoulder handbag on my right-hand side. He was perhaps five years old, coming no higher than my waist, wearing a T-shirt, shorts and sandals, very thin with dark, shiny hair. It seemed the most innocent of minor encounters. I thought no more about it.

His mother, a small, thin woman, was holding him by the hand and seemed to be urging him to do something. Such was the intensity in her voice, I thought she was scolding, telling him to mind his manners, not to jostle me and to move over. They both seemed to be of southern Mediterranean or even Arabic extraction: tourists drawn to Harrods, perhaps.

I continued walking, more slowly than usual, window- shopping because of the sales bargains in the shops and jewellers that line the short distance from Harrods to Knightsbridge tube station. The odd bump from the child followed but the pavement was crowded. I thought he was probably tired of being dragged around the shops, for it was indeed hot, and was being a bit naughty. And we all know that a five-year-old child is not threatening . . .

I went into a branch of the Hobbs clothing chain and picked out a skirt from a rail near the door. As I turned I felt a hand in my bag. The child, under the tutoring of his mother, had taken my purse. The handbag catch had been undone as I walked along.

I saw the pair turn and retreat quickly from the shop. But they were not fast enough, and I ran after them, anger fuelled by disbelief.

They ran across the traffic-filled road and I shouted 'Thief, thief]' I chased them all along the north side of Knightsbridge, shouting for help all the time. No one joined in, but the pair split up. If I had been ruthless, I suspect I could have caught the boy, who was lagging behind the adult. But I was in a state of amazement that a small child should be used in this way. And I felt an instinctive reticence about bagging him, separating mother and child.

As I stopped chasing I found to my horror I was still clutching the skirt I'd been looking at in the shop. Shocked, I felt I was a thief, too. So I went back to Hobbs, where the assistant at the till by the door had seen everything and had telephoned the police. The girl said that these tiny pickpockets were commonplace. The policeman who later interviewed me on behalf of the Chelsea police station said that, indeed, this had become a particular problem in that part of London.

The most chilling thing, he added, was that when small children were caught no one turned up for them. They were often abandoned by their adult operators: the woman may well have not been the boy's mother.

I had been conditioned by the almost primitive and touching image of a small child battling to stay with its mother. But perhaps he would have been saved from a life of exploitation?

Though the day was sunny, I felt that I had had a brush with a modern Fagin's den, a Dickensian side of London that I had not suspected existed. I have been the victim of an attempted purse snatch before. But then it was more obviously threatening, a brush with a large teenager on a tube escalator. It was the age and small stature of the child that so disarmed me.

What I have noticed in the past 10 years is that every experience of crime makes one more careful and suspicious. There is a distinct loss of innocence. My behaviour is modified by real life, not a fear of potential crime. After experiencing four burglaries, I live in a house with a monitored burglar alarm. After a thief entered from the garden and stole my handbag and husband's jacket, I lock the French windows when I go upstairs, even for a few minutes, in the middle of the day.

Now, sadly, I find that I am holding my handbag far more carefully, cradling my arm around it in the street, swivelling suspiciously at every innocent jostle from a child. In my first trip after the incident, taking my children to John Lewis to top up their school uniform, I spent an extremely uneasy interlude at the crowded McDonald's opposite.

The outcome of this story is not all grim, however. The pickpocketing child dropped my purse in the gutter when I started chasing. An honest woman picked it up and waited patiently near the shop door until I came back, and returned it with the money intact. There was a silver lining. But how much better not to have to go through life eternally vigilant.