Why are the number plates in UK different Colours?

Is there a practical reason why UK vehical registration number plates are required to be white at the front and yellow at the rear?

Mike Meredith, Bath England

• They are also reflective and so one can tell at a glance whether they are approaching or moving away. White lights are required at the front so the white plate is also at the front.

  Jack Hill, St Albans England

• Jack Hill said: "White lights are required at the front so the white plate is also at the front." Using that logic, why aren't rear number plates red?

  Alasdair Patrick, Irvine, California USA

• In the assumption that Alisdair's question in good faith (rather than the wit I really think was intented). White and Yellow backgrounds are the clearest distinguisable options for dark letters and you may as well match the number plate with the lights where it can be; putting the yellow to the rear by default.

  David Cockling, Isle of Wight UK

• It's a good question for us non-British. I can't come up with any other country having different colored plates on the same vehicle. So a) why the two colors, and b) why these colors in those positions.

  Paul Hartvigson, Copenhagen Denmark

• I believe it was a standard set decades ago, for whatever reason. Many number plates around the world are not just black on white or yellow. Here in Australia we have dozens of colour combinations - white on black, white on red, gold on black, even several options of different character colours on a multicolour screen-printed background such as a cityscape or landscape.

  Chris, Mt Victoria, NSW, Australia

• Until the early 60s when reflective plates were imported from France, all UK plates were black on white. Somebody's whim changed rear plates to yellow. Co-incidentally, all French headlamps were yellow at that time - which continued until very recently. Le Mans 24-hour race restricts the slower cars to yellow headlamps, which provides vital information for other competitors. Yellow plates mean nothing.

  William Drake, Grandvaux, Switzerland

• The reason for a yellow plate at the rear and white at the front is because it is illegal to show a white light to the rear at night, and that the law includes reflectors in its definition of what constitutes a light. This was before the days of reversing lights, for which the law was amended so that if you are reversing you can show a white light in conjunction with a red light.. Also Yellow & Black are the boldest contrast you can get and thus enables them to be read at the greatest distance.

  Jon Ellis, Lancaster UK

• My country also uses front white plates and yellow rear plates. I think it's because you are able to tell which is the front or rear of the car by seeing the number plate, taking into consideration oddly shaped vehicles.

  Grace Chan, Singapore Singapore

• Adding on to the above answer, Black word on yellow background is best visible to human eyes and Black words on white background are best visible to traffic camera's and other electronic equipments. So they have so....

  Umendra Singh, Oxford UK

• For all these practical reasons that the UK have different colours of reg. plates on the front ad rear (and also France) i don't know why many other countries don't have the system. I could be fooling to have the same colour at night, if a car is coming towards you or reversing. In my country, they are white for both the front and rear, but the country i have moved to (Bretonia) has the choice of either yellow for the front and rear or white on the front and rear

  Mateo Franccisco, Montagvia, Sallin

• Just about every country, including the USA, Australia and all other EU countries have white number plates at the rear of their vehicles. So why can't the UK (GB) registered vehicles? I would like to put a white plate on the rear of my car, but would I get fined for doing so?

  Phil, Milton Keynes UK