���˿���

When police forces were first set up they consisted of ordinary constables and inspectors. A constable’s role was to patrol the streets and 'walk the beat'.

The nature of the police and the role of officers changed in the 20th century. There are increasingly a wider range of ranks within the police, eg Constable, Sergeant, Inspector and Chief Inspector.

• The Metropolitan Police set up the Flying Squad in 1919, so named because they used cars to react quickly to crimes, especially robberies. They were later renamed the Central Robbery Squad.
• In 1946, the Fraud Squad was set up, and in 1965 the Special Patrol Group was set up to deal with major emergencies and inner-city disturbances.
• Since 1878, each force has a Criminal Investigation Department (CID) that are detectives wearing plain clothes.
• There are also specialist murder, bomb and vice squads in each force.
• The Dog Handling Squad was set up in 1946.
• Counter Terrorism Command (SO15) was set up in 2006.

Increasingly, National Police units have been set up to deal with crimes on a national scale, such as the ACRO Criminal Records Office, and the National Wildlife Crime Unit.

Other national organisations have been set up by the government to support police work with specific crimes. For example, the National Crime Agency attempts to tackle serious organised crime.

Each police force now has a Forensic Department. Forensics is the use of science to solve crimes. At the start of the 20th century they developed a way of identifying every fingerprint. The Metropolitan Police set up a laboratory to test items of evidence. Police now use genetic fingerprinting – identifying criminals from traces of DNA in blood, hair or saliva samples for example. This is particularly useful in cases of murder or rape.