I think the case of Cambridgeshire highlights the problem that many counties without an ASU base experience these days. They're far enough away that a proportion of jobs that used to get a response, don't get off the starting blocks as experience has shown that due to the longer transit time, the chances of a result have diminished. It has become a self fullfilling prophecy.
Add that to the fact that a proportion of calls for attendance will find the nearest aircraft already on task in its 'own county' and with insufficient fuel to divert to Cambridgeshire and have time to do the job properly without going back to the nearest ASU for fuel first, and you have a second class service compared to what was there before.
Not having a go at NPAS here.....Cambs were struggling to afford the cost of a stand alone ASU before NPAS and like Norfolk, may have folded anyway.