On November 16, Guernsey Post will issue seven stamps for Guernsey itself and another seven for its neighboring island of Alderney — both part of the Bailiwick of Guernsey, a British Crown dependency in the Channel Islands off the coast of France. The stamps celebrate Christmas pantomimes, “Robin Hood” for Alderney and “Sleeping Beauty” on Guernsey’s stamps. This is is a type of musical comedy stage production designed for family entertainment developed in England and performed throughout the United Kingdom and elsewhere during the Christmas and New Year season.
Modern pantomime includes songs, gags, slapstick comedy and dancing. It employs gender-crossing actors and combines topical humor with a story more or less based on a well-known fairy tale, fable or folk tale. Pantomime is a participatory form of theatre, in which the audience is encouraged and expected to sing along with certain parts of the music and shout out phrases to the performers. Outside Britain, the word “pantomime” is often understood to mean miming, rather than the theatrical form described here.

While most of the stamp designs have already been revealed (we are still waiting to see six additional designs for Alderney), they are not yet even mentioned on the Guernsey Stamps and Collectibles website. What is most interesting about these particular items to Commonwealth stamp collectors is that they may just be the first to be released featuring the new royal cypher of His Majesty King Charles III.

In modern heraldry, a royal cypher is a monogram or monogram-like device of a country’s reigning sovereign, typically consisting of the initials of the monarch’s name and title, sometimes interwoven and often surmounted by a crown. Such a cypher as used by an emperor or empress is called an imperial cypher. In the system used by various Commonwealth realms, the title is abbreviated as ‘R’ for ‘rex’ or ‘regina’ (Latin for “king” and “queen”). Previously, ‘I’ stood for ‘imperator’ or ‘imperatrix’ (Latin for “emperor” and “empress”) of the Indian Empire.
Royal cyphers appear on some government buildings, impressed upon royal and state documents, and are used by governmental departments.
Wikipedia
The cypher is the personal property of The King and was selected by His Majesty from a series of designs prepared by The College of Arms. A Scottish version of the cypher features the Scottish Crown, approved by Lord Lyon King of Arms. The decision to replace cyphers will be at the discretion of individual organizations, and the process will be gradual. 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.

While these Christmas stamps might be the first to bear it, the Charles III cypher is already being postally used by the Royal Household for franking mail. I am not real sure how to receive the cancellation other than write to Buckingham Palace and hope for a reply. It is certainly worth trying. Good luck!