wardsidjame,
I have heard these points but can not find the "law" or guidance, or case law precedent outlining good practice and what the filters white or black list must or must not contain. We are a public space, a cafe, a shop a museum and a gallery. I wondered how Starbucks, BT, Stagecoach Bus, and most other coffee shops and the like are able to do it. It is not a matter of how to do it. It is the extent. As an open to the public place for all legal levels of social interaction, discovery, learning and exchange we are about being open. Safe yes, but as open as possible. So we want to apply exactly the right level of filtering as stipulated by industry standards and government guidelines not our own whim.