Tim Berners-Lee, inventor of the world wide web, put privacy into the spotlight last week when he warned social networkers that everything they post online might be read by friends and relatives, present and future.

Sir Tim's was the latest high- profile warning over invasions of privacy, particularly on the web. As going online has become part of everyday life there has been an associated rise in campaigns and lobbying by "privacy activists", who harry any business they believe is cavalier with personal details.