The concept of a national police air service is sound, or should be. By the use of a common aircraft type, the initial fleet purchase, maintenance, availability of spare airframes, crew training etc should become more cost effective.
Unfortunately it was introduced at a time of increasing financial constraints and those put in charge seem to have soon lost the plot, despite being given very sound professional advice. Even worse, those trying to give sound advice were seen as troublemakers and removed from post. The result was that not much (if any) money was actually saved, but operational efficiency was devastated. The whole concept of trying to replace a number of helicopters with a fewer number of unsuitable fixed wing was never going to work for no notice tasking such as vehicle pursuits. What service the taxpayer now receives seems to have plateaued, unfortunately that plateau is at rock bottom.