What will be the response?

There has been a spate of fatal or near fatal stabbings/knife attacks recently. Perhaps the most shocking was the fatal stabbing of a student on a train at the weekend. This is in the same week that the police are holding a nationwide knife amnesty, offering people the opportunity to drop knives into special bins in police stations, with no questions asked, whilst presumably being video-ed by the ubiquitous CCTV. What is the next step we can expect as a result of these awful crimes? Airport-style (and, I should say, public-building style) metal detectors at the entrance to every train and school? What is the correct balance here between the risk of harm to individuals as against the general restriction on liberty posed by enduring endless personal and property searches? And will policy responses be considered responses, or the type of knee jerk reactions of which we have seen so many in recent weeks?