What has always puzzled me is why there are so many separate codes for Police helicopters... I assume they rarely operate in the same airspace .............
In the North West, for example, there are at least five Police Air Support Units (N.Wales, Lancashire, Merseyside, Manchester and Cheshire ASUs), and quite often there can be three or more of their aircraft simultaneously working either Manchester or Liverpool ATC. Discrete SSR codes for each ASU therefore works well. It just a shame that when the ASU callsigns were re-organised, a while back, that Merseyside's and Cheshire's now sound so similar!
