My book, Darkness at Noon by Arthur Koestler is primarily in a prison. The book takes brief intermissions of setting into Berlin right after Hitler has taken it over around 1933, during this time period Rubashov (who is the main character) is a high ranking member of an extremist party of some sort. During the flash backs scenes of havoc are depicted as you learn of the inner turmoil of the dying extremist party. But during the majority of the book when he’s not having flash backs you read of some sort of communication thru tapping the prisoners use, torture and spiteful shows of power like starving Rubashov. The torture the guards in the prison use range from “steam baths” to savage beatings, the older guards are kinder but the younger ones are aggressive and menacing. These are really the only events that occur in the prison, this and Rubashov doing exercises, communicating to the cell next to him and having flashbacks.
This story can take place anywhere there are secret societies, no such thing as constitutional rights and extremely bad blood between the groups. I’d say this setting is not like Salisbury at all, Salisbury’s prisons I’m SURE are not this bad and the prisoners don’t get tortured in weird ways or tortured at all for that matter. I doubt Salisbury has any sort of extremist parties with powers such as these or would the feud become so bad that people would basically go to a savage war over it.