Alex,
In your area, the police would accept primacy of the situation in consultation with ARCC. While plans are afoot for the MAOT from the ARCC to take over full air to air co-ordination, the police helicopter would call you over to the (informal) nationally accepted scene of disaster frequency of: 123x1 to initiate some form of collision avoidance procedure.
There is currently an attempt by the Home Office/CAA to employ the efforts of the BHAB emergency services sub committee in the shape of HELP:[Helicopter Emergency Liaison Plan].
Believe it or not, other than this, the government, nor the military have any CO-ORDINATED means of aerial deconfliction at national disasters. Even after continuous testing of the system with incidents like the cumbria train crash recently, or even 7/7.
Basically it has been left to us and the mil to sort ourselves out. And that is what we have done with this system.
It has yet to be tested.................
