Jamie Grierson “King Charles III’s official monogram design released by palace” https://www.theguardian.com/uk-news/2022/sep/26/king-charles-iiis-official-monogram-design-released-by-palace
The monogram is Charles’s personal property and was selected by the monarch from a series of designs prepared by the College of Arms. A Scottish version features the Scottish crown, and was approved by Lord Lyon King of Arms.
It will be used by government departments and by the royal household for franking mail. The decision to replace cyphers will be at the discretion of individual organisations.
The process will be a gradual one and in some instances the cyphers of previous monarchs can still be seen on public buildings and street furniture, especially post boxes.
The College of Arms, which designed the cyphers, was founded in 1484 and is responsible for creating and maintaining official registers of coats of arms and pedigrees.
The heralds who make up the college are members of the royal household and act under crown authority.
On the same day, Royal Mail announced four stamps that feature portraits of the Queen, to be released in her memory.
The stamps – the first set to be approved by the King – will go on general sale from 10 November and will feature images of the late monarch through the years.
A photograph taken by Dorothy Wilding in 1952 to mark the Queen’s accession and coronation will feature on the second-class stamp, while the first-class stamp will include a photo taken by Cecil Beaton in 1968 in which the monarch is standing in her admiral’s cloak with her head tilted to the left.
A portrait taken in November 1984 by Yousuf Karsh will appear on the £1.85 stamp, and a photo taken by Tim Graham in 1996 of the Queen attending a banquet at Prague Castle during her visit to the Czech Republic will be the image on the £2.55 stamp.