From the EYFS: "Children must usually be within sight and hearing of staff and always within sight or hearing."
In other words it's legal to walk out the the nursery room and leave children on their own providing you are within earshot. I've always considered this as totally wrong. It kind of assumes that if any child gets into trouble they will call out in a clear voice "Help me! I need urgent assistance!". A child with something wrapped round their neck will make no sound so there will be no staff rushing in to help them. Same with cutting hair and a child having convulsions of some kind.
What do you all think?