A collar number, also known as a shoulder number, force identification number or occasionally as force number, identifies police officers, police community support officers, special constables and some police staff in UK police forces - other law enforcement agencies, such as Immigration Enforcement, have also adopted identification numbers. Although now displayed on epaulettes, it is still commonly referred to as a collar number. Although most forces issue a collar number to all warranted officers regardless of role, only uniformed officers of the ranks constable and sergeant actually display the numbers. In most forces it is simply a one- to five-digit number, but in larger forces a letter code may be added to indicate the officer's base area or unit. In some forces different types of staff are assigned different ranges of numbers, so a person's role can be deduced from the number, but these systems are force specific and there is no national standard. For the letters shown on riot helmets and the roofs of police vehicles, see Home Office radio callsigns.
France
In France, the wearing of the collar number is compulsory, save a few exceptions, from 1 January 2014.
United Kingdom
City of London
The Metropolitan Police Service started introducing collar numbers around the 1860s to increase accountability and gain public trust. Until recently, collar numbers consisted of a number followed by a single letter to indicate the division. In 1914, the force was reorganised into four divisions, each named after its police station: Moor Lane Police Station was destroyed in the Blitz in 1940, and A Division was abolished and distributed amongst the three remaining divisions. Cloak Lane Police Station was closed down in 1946, and D Division was transferred to the new Wood Street Police Station. The divisions after 1946 therefore stood at: In 1984, the force was reduced to two territorial divisions, based at Snow Hill Police Station and Bishopsgate Police Station, together with support divisions, and the divisions subsequently stood at: In February 2009, all the divisions were abolished and the force was divided into directorates. All officers' collar numbers were then suffixed by the letters "CP" rather than a divisional letter. Collar numbers are allocated as follows:
Metropolitan Police
A number, followed by one or two letters indicating the station/sector, borough, or unit. Current practice favours use of borough codes rather than station codes. Divisional area codes are still used to identify the areas themselves, together with the police station and vehicles nominally covering them, but not officers. A one or two digit number denotes a Sergeant, a three digit number denotes a Constable, a four digit number beginning with 5 denotes an officer of the Metropolitan Special Constabulary, unless they're attached to a 'Roads & Transport Policing Command' team, in which case the number will begin with an 8 and a four digit number beginning with 7 denotes a PCSO again unless they are attached to RTPC and they will start with a 6. Confusingly, MPS epaulettes display the letters over the digits, i.e. 81FH would show FH over 81 on their shoulder, which reads more like FH81. Ranks above Sergeant do not have collar numbers - officers are identified by name. An exception to the above is the City of Westminster borough. Westminster has over 1,500 officers therefore a three digit number system is too small. Until late 2009 constables and sergeants had four digit shoulder numbers beginning 1, 2, 3 or 4. With the amalgamation of Westminster Central and South in late 2009 the decision was taken to amalgamate all the shoulder numbers into one numbering system. All new officers joining the borough will be given the first available number and cross division moves will no longer result in the need for a new shoulder number. Specialist MPS units do not necessarily follow any of the above numbering rules, with both Constables and Sergeants having anything from one to four digits. All Metropolitan Police officers in uniform below the rank of Inspector are required to have their collar numbers on display at all times. It is increasingly common for higher ranks to display their warrant numbers on their epaulettes in addition to their rank.
From 2017 to 2019 the Metropolitan Police Service reformed the organisational structure of Frontline Policing from the existing 32 Borough Operational Command Units into 12 new Basic Command Units. † Some authoritative sources are self-contradictory and incomplete. Not all of these stations are currently operational. Further to this; letters on shoulders will denote borough or newly formed basic command units and not the police station an officer is based from. An example of this would be a PC working from East Ham Police Station in the borough of Newham; the PC would have KF on their shoulder and not KE. Similarly in newly merged boroughs a PC working from Holloway Police Station would have CN on their shoulder.
Sussex Police
All officers will be provided with a collar number which is also their warrant number. Prior to September 2018, this was deemed by gender for example CS123 would represent a male officer who's surname started with S, a female would being with a D, DS123 for example. The second letter would be the first initial of the officer, followed by a three digit number. In September 2018, this changed and all new officers warrant numbers start EA followed by a three digit number.
PNC codes and collar numbers
When a police officer or a member of staff is in a collaborative unit or department, the PNC code, which is a force identification number, is added to the collar number to prevent confusion between officers; e.g., 41-9999 would indicate a Hertfordshire officer. These numbers are only used in paperwork and are not seen on the officer's epaulettes.
Operational Support Staff and sworn Prison Officers in Her Majesty’s Prison Service bear collar numbers to aid in accountability in the service. Collar numbers bear two letters indicating which establishment the officer is based at and three random numerical digits.
