There have been two reports in the past week of men getting into trouble for hacking into the computers to spy on young women through their webcams. One man gained access by sending his victim a Trojan by email and the other allegedly used a Logmein remote-access client.

Sophos, which reported the first case, lists three others that have reached the courts. What is worrying, paradoxically, is that there are so few of them. The Home Office does not give numbers for 'traditional' Peeping Tom convictions, which are logged under 'miscellaneous sex offences', including flashing. These have hovered at around 10,000 a year in the UK for the past six years.

These are just the figures for the people caught and charged, and they probably represent only a fraction of the number of actual offences. So even if Peeping Toms are involved in only a small proportion of these cases, it's a fair bet that there are thousands of them active and many of them will be computer literate. And that is just in the UK.

You would not need to be a computer genius to find software capable of accessing a remote webcam, provided it could be planted in a remote machine. Millions of machines are already infected with Trojans capable of providing access.

Both the men in the latest cases appear to have left themselves wide open to discovery, one by trying to blackmail his victim and the other because the young woman involved noticed that her PC had slowed down. This leaves the question of how much is going on that is not discovered.

Security firms will stress the need to buy more protection. But surely the best rule, particularly for for wives and daughters, is: Never do in front of your web camera what you would not do in the street.