I don't know that the move from Exeter would make much difference to Police air support in Cornwall - historically, police officers there were wont to refer to the "Devon Police Helicopter", while officers in west and south Devon referred to the "Exeter Police Helicopter". Plenty of instances of the aircraft not being available for operational tasks because the crew were needed for a visit - or IR renewals - or whatever. I certainly flew once from Wilts to Okehampton to assist with a murder investigation one night (called off as we got to within 5nm), and also remember being tasked from Brum on another night (stood down before we'd left Brum CTR). Later, when flying air ambulance in the county, a policeman I'd known in a former employ told me that their traffic officers working the motorway had no SOP for using the heli (other forces I'd worked with would only conduct a motorway pursuit or stop under the watch of the aircraft) as they knew it would rarely/never be available - despite Middlemoor's perfect position next to the M5/ANPR locations.