Following the discovery of a rare Edward VIII pillar box in Maidstone’s Week Street, comes news of a potentially even more unusual find.

At first glance the red pillar box outside Barming Post Office looks like any other – except it has a double collection plate. That is the clue indicating this pillar box was in fact originally a blue air mail postbox.

A commercial air mail service started in Britain as early as 1919. By the early 1930s, Imperial Airways was operating regular airmail services to Europe and the British Empire.

In 1930, special air mail-only pillar boxes were introduced and painted bright blue to distinguish them from ordinary post boxes.

The blue colour was said to be “RAF blue” – and was also incorporated on air mail stamps, where it is still in use today.

The first such postbox was outside the General Post Office in King Edward Street in London. Soon there were 139 in the capital and 174 in the provinces, including this one at Barming.

The service was suspended in 1938 as war approached. Although air mail was resumed in 1945, the special postboxes were no longer required as by then it could be posted from
anywhere. They were gradually either removed or painted over to become regular postboxes.

Only one blue air mail box remains in its original position and in its original blue livery – outside Windsor Castle. The British Postal Museum in London and the Isle of Wight Museum also have blue boxes.

Originally, the boxes had a blue oval plate saying air mail on the top. The double plate on the front showed collection times on one side and air mail postage rates on the other.

If you look closely at the Barming pillar box, you will see that where the red paint has chipped off, the air mail blue shows through.

In addition, the words Air Mail Only are also engraved on the box.

It is not known how many blue boxes survive disguised as ordinary post boxes.