I picture the constables of the RHC not having too many named ranks and more like an office type environment. Reading the Players Guide says the RHC branch in flint has about 20 constables and about a hundred researchers, office assistants, laboratory technitions, security guards, carriage drivers and the like. Now with 20 constables i can assume there are 4 parties of 4 to 6 constables each. the players being whatever team name your players choose, and i do see some nice group names here on the forums.
my choice names are as follows:
Constable (only 15 or 16 in the flint branch)
Sergeant (team lead, an npc Sergeant would probably be Carlao)
Inspector (or Assistant Chief Inspector)
Chief Inspector (Margaret Saxby)
Viscount Inspector (This role oversees all branches of the RHC)
A bit of history (thank you wikipedia), Viscount was a non hireditary, administrative or judicial position. This leads me to think of Nigel Prince-Hill where to retire, another would take his place as Viscount Inspector.
If we use a ratio of 1 police officer to every 400 citizens, and with Flints population at 800,000 that leaves us with just about 2000 police officers. Thats a huge increase over the amount of active duty constables. With the relation between police and constable, I picture the police as being very rigid and structured and the constables being much looser. With rank and jurisdiction, the constables should take point and hand off to the police when everything is under control.
Hope this helps! im curious to see what other DM's are doing in their games.