British stamps are the only stamps in the world that don't have the country of origin printed on them. They simply display the reigning monarch's head. This is because Britain was the first country in the world to issue stamps in 1840.

The rarest UK stamp is the Edward VII 6d overprinted 'IR Official', intended solely for use by the Inland Revenue. It is thought that no more than six used stamps exist, each with a catalogue value of £65,000.

Her Majesty the Queen approves all stamp designs before they are printed.

Royal Mail stamps do not feature specific living people other than members of the Royal Family.

Perforations did not appear on stamps until 1854. The Penny Black had to be cut from its sheet with scissors.

Special Christmas stamps were first issued in 1966. Royal Mail now prints more than 480 million Christmas stamps a year

The gum on a definitive stamp (those with the Queen's head) contains 5.9 calories while a special stamp has 14.5 calories.

There are over 5.4m people in the UK who collect or buy stamps as gifts - 11.5% of the population.

The British designer David Gentleman has designed more stamps than anyone else - over 100 issues

A gravure press running at full speed prints around 24,000 Special Stamps per minute.

The Treskilling Yellow of Sweden is the world's most expensive stamp. It was sold for £1,429,000 in 1996.

The world's rarest stamp is the 1856 British Guiana One Cent. Only one of them exists!

The Great Stamps of China... At 21cm x 6.5cm these monster stamps would have taken some licking when they were issued early last century.

The Columbian state of Bolivar issued the smallest-ever stamp in 1863, measuring just 9.5mm x 8mm.

A banana-shaped stamp was issued by the Pacific island of Tonga.

Musical post... In 1973 Bhutan in the eastern Himalayas, produced seven stamps in the shape of records - not only that, they could actually be played on a record player!

In 1998 the Dutch Postal Service produced a zero cent stamp. Despite having no value, people were told it could be used to send for letters within Holland.

Deadly serious collecting... In 1892 a rich collector was murdered by his friend because he wanted his extremely rare 1851 two cent Hawaiian 'missionary' stamp. The police found the missing stamp in the friend's collection and knew they had their man - the stamp was the only one in the world.

In 1903, the island of St Kitts produced a stamp showing the explorer Christopher Columbus looking through a telescope. One problem... they weren't around in his time!

There are currently over 200 countries producing stamps. In the last 150 years, nearly 500,000 different stamp issues have been produced by more than 600 countries.