https://drive.google.com/file/d/0B4X8tpb0l73sMmxOV1hlaDRTQUptelVqYTQ2WVY1aUsyZFJ3/edit?usp=sharing - ambulance block allocation - specific radio frequencies per channel
Channel allocations for various areas - London uses 9 channels
Pg 2 - locations with channel numbers
Former health regions