ppheli yes Sussex is a joint operation but they still need to land... or did I miss what you were getting at? Police ground units won't necesssarily be at all medical calls.
And you pretty much summed up the politics yourself! There was some rumour about similar joint police/ambulance outfit but nothing seems to have come from it. Ambulance service seems to have its own high level reasons for not using air support - can only be requested via top level duty manager...
There is a very strong reluctance to use (London) HEMS as if the patient is taken back to the London then the local hospital is, (apparently) cross charged and they don't like that.
Also heard a comment in HQ a while back "..why do we need a helicopter - we can always use Sussex/Kent/Berks/HEMS if we get desperate.."
PW