Old bill

Unknown. Suggested sources for the police officer and police force terms include: #Old Bill, comic character created by Bruce Bairnsfather. #Music hall song "Won't you come home, Bill Bailey", which references the Old Bailey criminal court. #William IV (reigned 1830-37), who became king the year after the Metropolitan Police were founded (1829). #Wilhelm I, Prussian Kaiser who visited the UK around the same time the custodian helmet was adopted (1863). #bill (“cutting instrument”) or billhook, weapons carried by constables of the watch. #bill (“written note of services rendered”), allegedly presented by a police officer to solicit a bribe. #bill (“draft of a law”), laid in Parliament. #Number plates for all public services, including police, registered by London County Council with the letter "BYL". ##Specifically, the cars of the Flying Squad. #Bill Smith, a popular police sergeant in Limehouse circa 1860s.