The mailbox bears King Charles' cypher and the monogram with the initials 'C' and 'R.
The first red mail pillar box to bear the cypher of King Charles was unveiled on Friday, keeping up a tradition dating back almost 175 years.
The new box has been installed on the High Street in Great Cambourne, central England, and local school children will get to post the first letters, and missives to the king himself about their interest in the environment.
The mailbox bears the king's cypher, the monogram that appears on government buildings which consists of the initials 'C' and 'R' - representing Charles's name and "Rex", the Latin for king - alongside a depiction of the crown.
One of Britain's most recognisable symbols, red pillar boxes appear on countless postcards and souvenir items, with about 115,000 in operation across the country.
The first post box was introduced in the 1850s, and their age can be traced by the royal cypher they bear, with the oldest dating back to the reign of Queen Victoria, Charles' great-great-great grandmother.
Although new boxes have been installed since Charles succeeded his mother in Sept. 2022, existing stocks bearing the late queen's cypher were used.
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