There have been several numbering systems used since motor vehicle registration first started in the first years of the 20th Century. Things got off to a fairly uncertain start, with variations to the original numbering system appearing in some regions. However, it is generally true to say that the very early number plates consisted of a letter code denoting the issuing authority, and a sequential identification number. Unlike more recent versions, this first generation of number plates had no year identifier.

Demand for registrations grew as the number of vehicles on UK roads increased, and a slightly more flexible format was devised, which would provide more information about the vehicle. This new format retained the principle of the regional identification letters, and the sequential ID number. The greatest innovation was the addition of a letter code at the end of the plate which indicated the year of issue. This had two major benefits: it enabled people (including prospective purchasers of used cars) to determine the age of a vehicle, and it meant that the number sequence used to identify individual vehicles could be reused each year, as the year letter would change. Because of the placing of the year code at the end of the character string, these new plates became known as suffix number plates.

The next significant change, when the suffix series had run its course, was a very simple one: the format of the registration number was simply reversed so the whole process could start again from the beginning! An example of the suffix format would be EXE 456L; in the new system the format would be L456 EXE, with the year letter coming first, followed by the unique ID number and the letter group, including the region code. Unsurprisingly, as the year letter came at the start, this generation of plates became known as prefix number plates.

With the number of vehicles constantly increasing, the prefix system soon exhausted the combinations available, and yet another number plate format was required. In September 2001 the current style of UK vehicle registration plates was introduced. The current number plate format consists of a two-letter regional identifier called the "local memory tag", a two-digit year code or "age identifier" and finally a three-letter "random element which provides the specific identification for each vehicle. An example of this current format is the registration BD51 SMR. "BD" is a code for Birmingham, 51 is the code for September 2001. SMR is a random letter combination which will be assigned to only one registration issued in any one area during any one "age identifier" period, thus uniquely identifying the vehicle to which it is applied.

Another important change is that registrations now change twice a year instead of once. The use of a two-digit code instead of a single letter allows for many more permutations, thus extending the useful life of the current scheme.

2: Number Plates Display Regulations This section explains the rules that set out how we are allowed to display number plates

When the new registration format was introduced in 2001, regulations governing the construction and display of car number plates were revised. These revised regulations apply to the number plates on any and all vehicles registered on or after 1st September 2001. They also apply to all replacement plates made and mounted on vehicles on or after the same date.

Number plates must now use one specific, mandatory typeface - a very simple sans serif typeface intended to make the numbers easy to read by both humans and automatic recognition systems which are increasingly being used by the police and other agencies. All hard-to-read variants such as multiple stroke and italic fonts are now prohibited. The one decorative variation still permitted is a 3D effect version of the mandatory typeface. Specifics of size and spacing are:

* Each character must be 79mm high and 50mm wide (except the number 1 or the letter I) * The width of each character stroke must be 14mm * There must be a space of 11mm between characters within the same group * Character groups must be 33mm apart.

Optionally, number plates may display one of the following national emblems:

* British Union Flag with "GB" * English Flag (St George Cross) with "ENG" * Scottish Flag (St Andrew Cross) with "SCO" * Welsh Flag (green dragon on green/white field) with "Wales" and "Cymru" * Euro Flag (circle of stars) with "GB". If the Euro/GB configuration is displayed, then the bearer vehicle need not display a separate "GB" emblem when driving within the EU.

The colours and reflectivity of number plates are also specified in the regulations, and there is a British Standard (BS AU 145d) which describes the physical characteristics of number plates, including: visibility, strength and reflectivity. Front plates must have black characters on a white background, while rear plates must have black characters on a yellow background. The British Standard also requires that a number plate must be marked with the following information: the British Standard Number, the name, trade mark, or other means of identification of the manufacturer or component supplier, the name and postcode of the supplying outlet. A non-reflective border is optional. There may be no other markings or material contained on the number plate.

3: Personal Number Plates We explain what personal number plates are... and what they are not

Personal number plates are not number plates which contain the letters that spell out a name or word. The registration system used in the UK isn't that flexible.

On the other hand, the number/letter combinations that are permitted on UK plates allows surprising scope for the approximation of names and words. This is achieved by the natural similarity between certain numbers and letters, and by the tendency of the human eye and mind to seek familiar patterns. By way of illustration, most readers will be able to deduce why a London plumbing company has equipped one of its vans with the registration DR4 1N. The resemblance is clear, even if the word isn't actually spelled out. That one small example pretty much sums up the principle. Of course, there are other kinds of plates sought by car owners: some want their initials, while others like to incorporate a meaningful number. The message is sometimes clear, as in the example above: sometimes it is deliberately cryptic, and only the initiated can share the joke.

In the UK it is permitted to buy and sell the rights to display registration numbers, and thus to transfer numbers from one vehicle to another. There is some paperwork involved, and some conditions that must be satisfied but, with the assistance of a specialist company, the process is fairly fast and easy.

4: Registration Transfers: Procedures and Regulations What you need to know if you want to buy or sell number plates

If you own a car which is registered and has a number plate, well, you could sell that registration number if you wanted to. Similarly, you could buy another and re-register your vehicle with the new number. It is a little more complicated than just changing the plates that are displayed on the car: the correct paperwork needs to be completed and the proper conditions complied with, in order for the whole thing to be legal. While the process is not hugely complicated, there are a number of potential pitfalls awaiting the unwary, so it really is advisable to engage the services of a professional company, such as www.regtransfers.co.uk to assist with the formalities.

The following conditions must be satisfied in order for a transfer to take place.

* Both the donor vehicle (the one from which the number plate is being taken) and the recipient vehicle (the one to which the number plate is being moved) must have current tax and MOT * The recipient vehicle may not be older than the year on the number plate that is being transferred to it. In other words, it is not allowed to make a vehicle seem younger than it really is by changing the registration number * If a car is to be sold, written off, or otherwise disposed of, the registration will be lost unless it is transferred from that vehicle before disposal. In the case of a write-off, the registration is not just lost to its former owner - it is lost altogether and cannot be reused.

It is possible to buy a registration, even if no vehicle is available to receive it. For example, a car owner may have a treasured personal number plate, but may wish to sell his/her car. If a replacement car is not ready, it is possible to transfer the registration from the current bearer vehicle onto a certificate of entitlement known as a Retention Certificate. When a vehicle becomes available, the number may then be transferred from certificate to the car - subject to the conditions described above. Registrations may actually be held on certificate indefinitely, so long as the certificates are renewed - a process that involves a modest fee payable to the authorities.

A professional company will be able to take care of all these points. The transfer process generally proceeds without problem and fairly speedily. Timescale is usually measured in days, with the main delays being simply the time taken for the necessary paperwork to be posted to and from the authorities.

So, there we are. This is a fairly comprehensive, yet concise, guide to the basics of UK number plates and personalised registrations. Of course there is a lot more to learn, but the information presented here should help the reader to avoid problems with displaying number plates legally. It should also help the reader to go into any registration transfers situation with at least a basic understanding of what is involved.

If further information or assistance is required, www.regtransfers.co.uk is the UK's leading independent number plates expert. Advisors are available to help between 8am and 11pm, 7 days a week on 01582 477333.