In the UK, there is an increasing culture that implies that all adults are dangerous to children, unless proved otherwise. We are terrified of a strange adult coming near a school (despite the fact that by far the majority of really nasty crimes against children are committed by family and friends, rather than strangers).
One result of this climate of fear is that we routinely expect people who go into schools on a professional basis to have a Criminal Records Bureau check - and there is going to be an even wider reaching scheme in place from next year, which has caused many protests from high profile authors, which seems to incorporate CRB checks, though I'm not quite sure how.
I've relied in the past on a CRB check done by a charity, but now I've joined an organization called National Association of Writers in Education, which will do the CRB check for me - because one of the ludicrous things about the way CRB checks are run is you can't apply for certification yourself, it has to be done by an 'umbrella organization.'
However, what really irritates me is that this is entirely unnecessary. As a visitor to a school, going in to give a talk to students, I expect to be accompanied by staff at all times. What do they think I am going to do? Knock out the staff member and have my evil way with the pupils? Admittedly, some schools I have visited in the past have been naughty about this and the staff members tend to try to disappear off to do a bit of marking, but it's usually not a problem to get someone to stay.
I'm sorry, it just makes me really angry.