Registration plates are attached to the front or back of most road vehicles - the obvious exception being pedal bicycles. In earlier times forged from metal, nowadays they are usually made of acrylic resin (plastic). Commonly measuring 524mm x 112mm (although occasionally they are more squarely shaped, measuring 285mm x 203mm) they display a series of letters and numbers unique to each vehicle. While many countries have their own unique systems for allocating the sequence of letters/numbers, in mainland Great Britain this is the responsibility of the DVLA (Driver and Vehicle Licensing Agency). Areas off the mainland, Northern Ireland, The Channel Islands and the Isle of Man have their own systems - the Isle of Wight does not, however. These items are also referred to as number plates, a vehicle index or, in the USA, license plates.

An interesting feature of the British number plate is that the front one has black letters on a white reflective background whereas the back plate has a yellow reflective background. It is a legal requirement that the letters and numbers are of a specific size (50mm) on a reflective material. The font may not be customised (italicised etc) and the plate must be kept readable (clean). Failure to comply with these rules means that vehicle owners run the risk of being fined.

Why Have Them?

Car registration plates are a way of identifying different cars. Imagine that you had just seen a little old lady knocked down on a pedestrian crossing. Without a registration plate, you'd only be able to tell the police that it was a blue Ford Escort desperately in need of a wash. How much time would it take the police to find and question all the owners of said make, model and colour car? With a registration plate you need only say the car registration number and a quick look on the police computer and the boys in blue can be round the offender's house in double-quick time.

How Are the Numbers and Letters Ordered?

One of the more exciting features of British plates is that they usually allow you to identify the age of a car (this is not always the case if a car has been re-registered or a personalised plate is transferred). The registration system has evolved since its introduction in 1904 and different formats for ordering the number and letters have been used as the number of vehicles on the road has grown and combinations have run out. The system applies to about 99% of vehicles, but exceptions can be found.

Early Registrations

The original registration system was introduced in 1904 and had one or two letters followed by up to four numbers - ie, X 9999 or XX 9999. The letter codes represented the place of origin, for example A represented Greater London and EL represented Bournemouth. The complete list of area codes are provided by a website that also holds useful information on the pre-1963 years.

Dateless British Marks

When the one- and two-letter combinations ran out, an extra letter was added to the start of the plate and the format, now referred to as Dateless British Marks, and it became XXX 999. When areas ran out of combinations they simply reversed the order of number and letters to give the Reversed Dateless British Marks format of 999 XXX.

Suffix System

In January 1963, the Suffix format started to be used by some areas and from 1965 it became a legal requirement. The sequence became XXX 999X where the final letter represented the year the car was first registered.

Therefore, vehicles with a plate ending 'A' eg ABC 123A had been registered during 1963. January 1964 began the 'B' registrations, 1965 'C', and so on and so forth.

There are few 'E' registration plates in circulation. In 1967, the authorities decided that the registration month should be changed from January to August. Therefore, 'F' plates are for cars registered in August 1967 through to July 1968. The system continued on: G - 1968, H - 1969, J - 1970 and so on, missing out 'I', 'O', 'Q', 'U' and 'Z' due to the possibility of mistaking them for the numbers '1', '0', '2' and the letter 'V'. These letters were still used in the initial three-letter part of the plate, though.

Prefix System

The Prefix system was introduced in August 1983 and follows the format X999 XXX. It was while this system was in use that allocation representing area codes via the second and third letters ended. Plates continued to be issued every year with August seeing the introduction of a new letter. A - 1983, B - 1984, C - 1985 and so on.

Once again letters 'I', 'O', 'U' and 'Z' were missed out. This time however 'Q' was reserved for use in special cases. These rarely-sighted 'Q' plates indicate a vehicle of indeterminate age. In most cases these vehicles are either imported or specially built: kit-cars, converted lawnmowers etc.

Status Symbols

With the suffix or prefix indicating the year a car had been first registered, the new plates issued each August became quite a status symbol. It also had the effect of helping to determine a vehicle's re-sale value. As a result of these factors, people considering buying a car in June or July would wait until August so that they could have the new letter to display to their neighbours. For the car industry, this created problems with peak sales being confined to one month of the year, rather than spread evenly throughout. To counteract this, new plates started to be issued every six months in March and September.

'S' plates were used on cars registered in September 1998 with 'T' plates being issued in March 1999 and the system continuing through to 'Y' March 2001.

Current System

From September 2001, the order of letters and numbers became XX99 XXX. In a return to area coding, the first two letters identify where the car was registered, the numbers represent the date of registration and the final three letters are random.

Personalised Number Plates

During the 1980s decade of rampant greed and ostentation, personalised plates became desirable status symbols. Owning a plate with your name on it (C1LLA or J1MMY for example) was considered to be the height of street cred. People try to form words using the most bizarre combinations; for example using an 8 or 3 as an E almost works, but a 7 for an A - no chance. Bad luck M7RK N.

The market for personalised plates has now reached a stage where the vehicle licensing authorities run a computer program before each registration period. This program identifies plates that may have significance to people and they are not issued as part of the normal registration procedure. Periodically auctioned, individuals and businesses will pay thousands of pounds for them.

Not all combinations of letters and numbers are issued on registration plates. Ones that can be arranged to form objectionable words are retained by the authorities.

International Recognition

In addition to a registration plate, many cars also display a small oval-shaped sticker containing two letters indicating their country of origin, eg GB - Great Britain. Since March 2001, it has become legally permissible for vehicle owners to use a number plate that has the European Union flag followed by the two-letter country identifier on the left side, preceding the actual registration number.