The names of these products tell the story: Net Nanny, SurfWatch and CyberSitter. All are designed to do what mums, dads and teachers don’t have the technological know-how or time to do: stop nasty stuff getting on the screen.

CyberSitter (Pounds 29.95) is the latest software to hit the market and the first to be produced in Britain. Says Daniel Power of Pow Distribution, which has developed the program: “CyberSitter benignly sits in the background and prevents children from accessing certain sites. It also logs sites and monitors messages.”

This means a kind of surveillance as well as a censor function, allowing parents and teachers to keep tabs on where children have been or tried to gain access to. The product works like this: when a young innocent does the unthinkable and puts in a search for “sex”, the Sitter replies that it is not available. Not only is it a censor, but it is an invisible one that lies through its teeth.

Mr Power admits that his program is no more infallible than any of the others. “These filters can be broken through,” he says. “A 15 or 16-year-old hacker could get through it, but the majority of children won’t.” The filters on some of these products can be activated wrongly, too. One story doing the rounds of Cyber circles is that of little Jimmy who keys in “Essex” for help with his geography homework. What he gets is a decidedly unhelpful computer crash because “sex” was registered. A similar drama has descended on the poor unsuspecting child who typed in “subject.” The dirty-minded censor saw the letters “b” and “j” in suggestive proximity, assumed that the kid was looking for “blow-job” and promptly shut down.

What does Mr Power think of all the negative press attention focused on the Internet? “The media hype’s good. It’s created a demand from parents. But it’s all a bit of an insult to parents, too as if they have no control over their children. These products are definitely for the yuppie parents market.”