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How do car number plates work?

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We all take the number plates on our cars for granted, but why do we have them? And are they a random jumble of letters and numbers, or is there some way of understanding them? 

What are number plates for?

Number plates show that your car is an officially registered, road-legal vehicle.

The need to register vehicles goes back to the early days of the motor car. Since 1904, all motor vehicles have to be entered on an official vehicle register and display plates made up of a collection of numbers and letters. This makes sure that all vehicles can be traced in the event of an accident, or is involved in some kind of breach of the law. 

Number plates have to be rectangular or square in shape, with the exact size of the plate and how the letters appear laid down in law. The number plates at the front plates have to be white, while the plates at the back have to be yellow.

What is the system for number plates?

The current system of vehicle registrationvehicle registration for mainland UK (Northern Ireland has a different system) dates back to 2001. It was introduced because we were running out of letter/number combinations under the old system and it was thought that the new system was easier to remember by witnesses to accidents or incidents.

The system uses seven characters: two letters, followed by two numbers, followed by another three letters.

The letters I, Q and Z aren’t used, because they look too much like a one, zero/nought or two

What do the first two letters on a numberplate mean?

The first two letters – called the location identifier – show the area of the country where the car was originally registered. There’s a logic to these. For example, vehicles registered in London start with an L, those registered in Wales (Cymru, in Welsh) start with a C and Scottish-registered cars start with an S. 

The rest of the country uses either letters from the county (E for Essex, Y for Yorkshire, etc) or a name given to the area of the country, such as F for Forest and Fens (Nottingham and Lincoln), or G for Garden of England (Kent and Sussex). 

What do the first two numbers on a numberplate mean?

The two numbers – called the age identifier – signify the half of the year the vehicle was registered in. 

There are two new registration periods: March and September.

March to August cars use numbers that are the last two of the year: 17 for 2017, 19 for 2019, for example. 

September to February registrations are different. For years starting with a zero (2001 to 2009), the registrations start with a 5, so cars from September 2001 have the number 51, 2002 are 52 and so on. 

Years that start with a 1 (2010-2019) use the number 6 after September, so the new cars from September 2019 use 69. From 2020, post-September-registered vehicles will use numbers starting with a 7, so next year they will be 70, etc.

What do the last three letters on a numberplate mean?

The last three letters on a numberplate are random. Car dealers are allocated batches of registration numbers and when they’ve used up their allocation, they receive another batch.

The current system will be in use until February 2051, when the government and DVLA will have to come up with a new one.

Personalised number plates

The DVLADVLA sets aside any registrations that it thinks people might want as personalised numbers plates. It makes money from selling them at specialist auctions it organises a few times a year.

This means that it’s possible to have a number plate on a car that is from a year before it was actually first registered. For example, a plate from the Birmingham area starting with BO followed by the number 55 (after September 2005) and a person’s three initials or name (BOB, perhaps) could be fitted to a brand-new car from 2019.

However, you can’t use a newer plate on an older car – a 19 plate on a car from 2007 car, for example.

The number plates of older cars

If you have a car from before 2001, your car will have a completely different system, which uses three numbers, three letters (the last two being location identifiers) and a letter at the beginning, which related to a year.  

The system started in August 1983, so the letter at the beginning of the sequence was A. Cars registered after August 1984 had the letter B. This continued until 1999, when the government introduced two registration periods a year. By August 2001, when we reached Y (Z looks too much like 2, so it wasn’t used), it was time for the new year-based system. 

Even older cars from February 1963 to July 1983, used a similar system, but the year-identifying letter was at the end, preceded by three numbers and three letters. 

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