The protection of children whilst using the internet is a highly emotive subject. There can be few who think it a bad idea. I have 4 kids who are heavy internet users. I don’t want them to come to any harm.

New MP for Devizes, Claire Perry, last week called for a change in regulations to require all UK-based Internet Service Providers to restrict universal access to pornographic content by implementing an opt-in system that requires verification that a user is over 18 for access to such material.

From a philosophical standpoint the fundamental principles of what Claire Perry wants are 90% ok – the 10% that are not ok being the right to privacy of people who might want to legally surf online porn but are not inclined to want to reveal their identity in order to do so. The problems come from the practicality of what is being asked for.

Website filtering is governed typically by the inclusion of a blacklist somewhere in the ISP network. User requests to access websites are compared with the blacklist and if the site is proscribed then access is denied. In the same way if an opt in is required it would happen at this stage. Parental controls usually involve a password being used to allow or deny the access.