Old time punishment
All of the "answers" (though they aren't answers really since they solve little) appeared to
be based on the supposed need
to understand disruptive behaviour.
In the old days, certainly when I was at school and when the kind of debate that the headteachers had would not have been needed, there was no such attempt to "understand" bad boys (girls were always better behaved). They were punished and that stopped the disruption.
I do not apologise for my apparent hard line. The people who need understanding are the pupils in the class, and their teacher, who want to get on with their work.
Corporal punishment was effective. It won't come bak, but I never heard anyone in later life complain about punishment speedily administered for offences that deserved it. The supposed damage to people is only in the minds of educational psychologists, who always sit on the front benches of wishy-washy
I do not envy headteachers their dilemma nowadays, and it is clear from your report that they are thrashing about (no pun intended) for a solution to discipline problems in their schools. The only advice an old-stager can give is: the interests of the many are more important than "understanding" the few.
The consequences of recent failings are daily seen in the vandalism, muggings, house breakings and car thefts committed by pupils and former pupils whose families have failed to bring them up properly and who need the kind of discipline which officialdom puts beyond the pale.