Lessons need to be learnt. I can't speak for GMP or BTP but we must have plans for major incidents. Its always chaos when large scale incidents happen but having an action plan to fall back on gives some structure to it. Operational Inspectors must be trained in dealing with critical/major incidents-in my force it does not happen, you are thrown in at the deep end.
We must communicate with other emergency services and neighbouring forces better. Moreover we must have more emergency services available to deploy, esp police and ambulances in the first place.
Staffing/resources are never planned for what if the worst happens, only to get by-and we usually manage it.
Was there an RV point set up? Was there a command structure put in place in quick time and was there a joint control/forward control point set up, again in quick time.
It is appalling that it took so long to declare it a major incident, to get the medical assistance there quick enough-yes its easy in hindsight but I have spoken about these things professionally for many years.