The jury took an hour to decide that Peter Harvey was not guilty of attempted murder. Indeed, as the judge said, it's hard to see how there could be any question of intention under the circumstances.
The premeditation here was all on the part of the pupils who cynically plotted to provoke a stressed man into losing control while they filmed the result. Well, they certainly got what they wanted.
Teaching is an anomaly, a job in which any sign of perceived weakness will be exploited and yet teachers are hedged about with draconian rules about how they may deal with disruption, to the extent that pupils have developed a 'can't touch me!' attitude.
I am not advocating a return to corporal punishment - although the formal public belting of the school bully in my primary days had a markedly beneficial effect for the rest of us - but when a detention, or even a suspension, can be summarily overruled, the message the pupil receives is that his teacher has no sanctions available.
In addition, the class will be fully aware of the 'Rantzen effect' - the common assumption that children do not lie about assault - which allows a malicious pupil to engineer the suspension of an innocent teacher with unfounded and unsupported allegations.
It's easy for the public at large, watching the top dogs of the NUT in action, to assume that all teachers join a union because they are militant activists. In fact, the reason many of them join is the legal support and appropriate professional advice available to members. It's unlikely any specialist counsellor would advise a classroom teacher to 'let his anger out'.
For most teachers, union membership is more like having car insurance: horribly expensive and seldom claimed on but absolutely essential in case something goes horribly wrong.
Update: I am indebted to JuliaM for this from the Daily Mash; black humour at its finest.
1 hour ago