Officers ranks are shown by the epaulettes which are worn on all police uniforms.
Every police officer is given a unique number in the force they join, rather than nationally. This means there could be a PC 989 in Thames Valley Police and an officer with the same number in Nottinghamshire.
In larger police forces where the police numbers are greater than those which can fit on an epaulette – like the Metropolitan Police in London where the numbers are greater than 20,000 - a divisional letter may be included to show which area of the force they work in.
Warrant numbers are shown on the epaulettes of Constables and Sergeants only.
Below you can see the rank structure of Northumbria Police and the epaulettes they wear: