Can't the police fly the plane from SOU? They can position the helicopter somewhere else - Dorset police fly the helicopter from their divisional HQ at Winfrith...I'm sure they have caught a few people riding their bikes on the pavement with it too.
I don't see why they can't share the airfield with GA - We used to have the Air Ambulance based at our field and it was no problem at all. Mind you, try getting permission to land a helicopter at the MCA base at Portland....no chance.
I'd love to see it an active GA airfield - it beats Southampton. I occasionally have to go to Walsash and it'd be ideal.