The question of whom the police serve, and whose order they impose, is once again up for debate. But it is as old as policing itself. A political cartoon by Charles Jameson Grant, sold for a penny or two on the streets of London around 1834, depicts the British secretary of state addressing members of London’s recently formed Metropolitan Police Force. “My lads,” he says, “you are always justified in breaking the heads of the public when you consider it absolutely necessary for the maintenance of the public peace.” The assembled constables, a rough-looking crew, appear perfectly capable of such a task. “By Jasus I wish your honor would give us a few throats to cut,” one says, “for we have had enough of breaking heads.”

Just about five years old at the time, the Metropolitan Police had already earned a handful of unflattering nicknames, as noted in the cartoon’s title: “Reviewing the Blue Devils, Alias the Raw Lobsters, Alias the Bludgeon Men.” Britain’s soldiers were colloquially known as lobsters, because they wore red coats, so in an effort to quiet fears that the police would be a kind of occupying army, the Metropolitan Police wore blue instead. Many early opponents of the police suspected that the difference was only cosmetic; they worried that it would take only a little hot water for the men in blue to show their true color.

London in the early 19th century was a sprawling and disorderly metropolis, divided into scores of parishes, each responsible for hiring its own night watchmen and constables. In cases of great civil disturbance, order was restored by the army. In 1829, after years of opposition, the home secretary, Sir Robert Peel, finally persuaded Parliament to institute a professional police force in the rapidly growing areas around the capital. Skeptics saw the police as a tyrannical import from the Continent; Paris, Vienna, Berlin and St. Petersburg had already created local police forces, and they were regarded as agents of state oppression. To address these criticisms, Peel took pains to distinguish his nascent police and demonstrate that the Met would be answerable to the people, not the king or private interests. Not only would they wear blue, but, like many ordinary citizens, they would also sport top hats. And they would not, except in rare circumstances, carry firearms.

Peel’s vision was highly influential in the formation of the New York City Police Department in 1845, and he is now regarded as a father of modern policing. Peel’s name is perhaps best known in association with the nine principles of policing, which remain fixtures in police academies throughout the English-speaking world.