I found this interesting. Here in the US we call them reserves. The city where I live has never used them, but smaller departments and the sheriff's department does. In my younger days I used to ride with the police, but it was casual and I never wore a uniform. I was able to do it mainly because no one had the nerve to say no. There are so many state regulations now this type thing wouldn't be allowed. It was great fun back in the day most of the time.
No matter the country, it seems a universal rite to give nicknames in police and military units. Sometimes they're based on names, appearance, or odd situations. They aren't always complimentary.
This evoked some good memories.