The first class stamp has had a royal makeover to mark the Queen becoming the longest reigning monarch in British history.
In honour of Her Majesty's record-breaking reign, the classic 63p stamp has switched from its regular red to regal purple for the next 12 months in celebration.
The stamp features the monarch's profile by sculptor Arnold Machin.
And its iridescent overprint, which usually reads "Royal Mail", now bears the text "Long to Reign Over Us", Royal Mail revealed.
It is the first time the colour purple has ever been used for what is known as the First Class Definitive stamp.
Andrew Hammond, stamps and collectibles director at Royal Mail, said: "Royal Mail stamps mark the most significant anniversaries and landmark events in the life of our country.
"We are proud to commemorate Her Majesty becoming the longest-reigning monarch in UK history."
The new stamp, along with a collection of four others, has been issued on the day the Queen becomes Britain's longest reigning monarch.
The miniature sheet of stamps includes a 1st class stamp featuring William Wyon's City Medal head of Queen Victoria - the country's previous longest reigning monarch.
The image on the Penny Black - the world's first postage stamp - was based on this portrait, which came from a sketch of Victoria when she was 15 years old.
Another 1st class stamp features Dorothy Wilding's three-quarter profile photograph of Elizabeth II which was printed on British postage stamps from 1952 until 1967.
There are also two £1.52 stamps - the first showing the Badge of the House of Windsor with the Castle's Round Tower of Windsor Castle flying the Royal Standard and the second containing the Queen's Personal Flag, designed in 1960 for use in Commonwealth countries. It includes an "E" with a crown, surrounded by a garland of roses.
:: The stamps are available at www.royalmail.com/theroyalconnection, from Post Office branches or by calling Royal Mail on 03457 641 641.