PAN,
Perhaps if you have over estimated the size of the town, you have over estimated the size of helicopter needed to police it.
If a force area was the size of a town like, lets say Rugby (pop 62,000), then it probably wouldn't be able to afford even a Robinson. If that was the case, the whole town could be cordoned off after every incident and the force microlight could be called in.
Either way I guess you would get pretty bored buzzing your 900 around such a place.
Nah!! didn't yesterday.