In the UK, the ranks of police detectives aren’t obvious because they use the initials rather than the words (like Sergeant, or Lieutenant). I thought I’d straighten it out for you so you can catch the insubordination when a DC contradicts a DS, or God forbid a DCI, in front of the squad room, or you’ll know when your main character is going to get his butt chewed by a superior. Also, it helps to know how far your main character has made it up the ranks. It speaks to a certain level of professionalism and ambition. I’m not sure how closely my rankings translate from TV to real life, but here goes from lowest to highest:
Detective Constable “DC”-the lowest rank of detective. Although you are thrilled to finally be a detective, DC is a position you are angling to get promoted out of. Often designated to grunt duty such as door knocking or procuring phone records and such, but may work a crime scene.
Detective Sergeant “DS”-a work-a-day rank that is the most common of the fictional detective characters. Often sent to process the crime scene. Some detectives spend their career at this rank. Of course, others want to lead investigations, not just work them, so they are climbing up.
Detective Inspector “DI”-in the fictional world, at this rank you are definitely leading investigations. But you are also high enough up the ladder that the bosses know you and may lean on you to get a result they need in order to look good.
Detective Chief Inspector “DCI”- One of the higher ranks, you will often find them leading specialty units or brought in to fix a disaster. Running an investigation from the office, answering to higher ups and being reported to by the DIs.
Detective Superintendent “DSupt” or “DSU”-The boss. Each local or regional CID (Criminal Investigation Department) has one. This is the detective that is often delivering a lecture to or covering for our main character.
Detective Chief Superintendent “DCS”-An administrator that is just below the chiefs. Usually 1 DCS per region.
Chief Constable-The “Chief”-a rank that has deputies and assistants who are sometimes referred to as “chief” as well. The Chief Constable would be the go-between for elected officials, the media and the police force. They often have to do the press conferences, so you will see the chief come into the situation either when the crap hits the fan or when someone solves a tough case.
Commissioner-An appointed position. The overall chief of the Metropolitan Police Force in London. You really don’t want to see him walk into the station!