It’s not working out too well for the brits

Yes but before that they were slave patrols. They still are - although they are more like debt slave patrols . It’s absolutely psychotic and immoral to earn money to kill another human or lock them in a cage.

Britain didn't have legal chattel-slavery in 1829, not since the early Middle Ages. (Some British colonies certainly re-instituted it quickly enough, though) Guilds "policed" their own members in the cities, when needed, but it usually wasn't, as courts were readily accessible and respected. Private security "thief-takers" also existed, but had no special authority, no monopoly organisation, and were at the mercy of the courts. Villages and clans did any required policing in the countryside.