On balance the right verdict was returned in my opinion.
There’s a feel on here from some posts that he made a conscious decision to do as he did. If so you’ve not understood the circumstances of the case.
I believe s. 3 (Provocation) of the Homicide Act 1953 extends to ATTEMPTED murder (I maybe wrong on this) –
Where on a charge of murder there is evidence on which a jury can find that the person charged was provoked (whether by things done or by things said or by both taken together) to lose his SELF-CONTROL, the question whether provocation was enough to make a reasonable man do as he did shall be left to be determined by the jury; and in determining that question the jury shall take into account everything both done and said according to the effect which, in their opinion, it would have on a reasonable man.
If there is no loss of control this defence is not available.
The court heard he’d snapped after being terribly goaded by these pupils. There is case law such as R v Humphreys [1995] where the court recognised a particular event can prove to be ‘the last straw’.
This was systematic and targeted abuse that resulted in a reasonable man employed as a teacher to lose his self control.