Together with the red telephone box, the scarlet Royal Mail letter box has to be one of Britain's most striking and iconic pieces of 'street furniture'.

With the advent of 'uniform Penny postage' in January 1840, the postal service could be utilised by all at a cost of just one Penny, irrelevant of the distance the letter needed to travel on the mainland. Then, in May the same year, the famous 'Penny Black' postage stamp was introduced so that letters could be pre-paid by the sender.

Initially, letters could only be posted at a Post Office but, as the availability of stamps became more widespread, people could purchase them in advance and send their letters when convenient. This small but significant change led to the novelist and postmaster, Anthony Trollope, experimenting with the concept of street posting boxes where people could deposit their letters for later collection. Trials were first carried out in Jersey, before a limited introduction in mainland Britain in 1853.

Public letter boxes fall into three main types: the pillar box, the wall box and the lamp box.

• Pillar Box - this is probably the most well-known, and is a tall, predominantly cylindrical or oval box that stands on the ground. Examples can be seen in just about every town and city in Britain.
• Wall box - as the name suggests, this type is usually set into a brick or stone wall so that only the red front plate is visible. These are often found set in walls near village stores, where the much larger pillar boxes are not required.
• Lamp box - often attached to a lamppost, this box is generally found in rural or remote areas. They are quite small in size due to the fewer letters they are required to handle

Although the common perception of post boxes are red, cylindrical and made from cast iron, the colour, shape, and production material has varied quite a lot over the years. Hexagonal 'Penfold' pillar boxes were very popular during Victorian times, and many of these can still be seen in towns and cities around the country. Rectangular boxes have been tried on occasion, but these did not prove to be so successful.

An experimental stamp vending machine was incorporated into a pillar box in 1932, requiring the box to be oval in shape with an aperture at either end - one for depositing letters, and one for vending stamps. By inserting a penny, two half-penny stamps, fed via a continuous roll or 'coil', would be produced. Several of these 'type C' combination design boxes still survive today, although we believe that the stamp vending operation is now redundant.

One thing that all Royal Mail letter boxes do have in common is the Royal Cipher of the reigning monarch. However, each monarch has their own individual cipher. Of the six ciphers that can be found, the most common are those of George V, George VI and Elizabeth II, but many earlier examples from the reign of Victoria and Edward VII can still be seen. Of course, the rarest cipher is that of Edward VIII who abdicated the throne on 11 December 1936. Three examples that we know of can be found at Maidstone in Kent, Stamford in Lincolnshire and the village of Walkford in Dorset.

One other rare Pillar Box of note is a blue, George V, overseas 'airmail' box. This type of box was only used for a short period between 1930-38 as the rapid expansion of air services to Europe and the British Empire, eventually made it redundant. The only surviving example still 'in situ' (pictured above alongside a red Elizabeth II pillar box and separate stamp vending machine) is located near Windsor Castle in Berkshire.