Until the mid-nineteenth century each parish appointed its own unpaid constable. His powers were limited: he could only detain a suspect if the victim reported the crime to a local magistrate. In the 1820s there was one constable for every 3,000 people living in London. In 1829 Sir Robert Peel formed the Metropolitan Police. The first professional police force were known as "bobbies" or "peelers."

The County Police Act of 1839 allowed magistrates outside London to appoint chief constables. Provincial forces, based on the Metropolitan Police model, were set up and crime detection and solving became more orderly.

When a felon's not engaged in his employment,
Or maturing his little felon plans,
His capacity for innocent enjoyment,
Is just as great as any honest man's
Our feelings with difficulty we smother,
When constabulary duties to be done,
Ah, take one consideration with another,
A policeman's lot is not a happy one...

When constabulary duties to be done,
A policeman's lot is not a happy one, happy one...

(Pirates of Penzance: W.S. Gilbert and Sir Arthur Sullivan.)