The new monogram to be used by Charles as the UK's new monarch has been unveiled and used for the first time on Tuesday, as the royal family's mourning period for Queen Elizabeth II comes to an end.

King Charles III's new cypher is designed by the College of Arms and shows his initial C intertwined with the letter R for Rex, which is Latin for King, and III is marked within the letter R with the imperial crown above the letters.

The all-in-gold royal monogram will be added to various public offices, papers, and street furniture across the UK over the coming months and years, replacing the Queen's cypher E II R.

The Court Post Office at Buckingham Palace became the first to make a frank or stamp post using the new cypher.

The post room at Buckingham Palace deals with around 200,000 items of mail each year, including invitations to events, responses to letters and cards received from members of the public and state business, the palace said.

The UK's College of Arms, founded in 1484, creates and maintains official registers of coats of arms and pedigrees.

The new cypher design would be one of several options prepared by the College of Arms and then chosen by the King.

A Scottish version features the Scottish Crown and was approved by Lord Lyon King of Arms.

The new monarch's monogram is intended for government buildings, state documents and some post boxes, with the decision to change the use of cyphers from the Queen to the King up to the discretion of individual organisations.

The process is expected to be a gradual one and the cypher of a previous monarch can stay in use for many years, just as those of Queen Victoria, Edward VII, George V and VI are still to be found on some post boxes in the UK.

Where changes can be made easily, such as digital branding, they can be made immediately and physical items such as signage or stationery will be replaced gradually over time as the need arises, the UK Cabinet Office has said.

Some of the other changes in store with the change of monarch include bank notes, which the Bank of England expects to be in circulation with the portrait of King Charles III by mid-2024.

That new portrait, replacing that of the late Queen, is expected to be revealed by the end of this year.

The UK's Royal Mint will also produce new coins in line with demand from banks and post offices" and that image is also yet to be unveiled.

According to the Royal Mint Museum, the tradition is for the profile of a new monarch on coins to face in the opposite direction to their predecessor.

Meanwhile, existing banknotes and coins will continue to be valid currency, with Charles and Elizabeth notes and coins being used alongside each other.

The Royal Mail says new stamps featuring King Charles III will enter circulation once the current stocks of stamps are exhausted.

At the conclusion of the royal mourning period, which was a week longer than the state mourning after the Queen passed away on September 8, the new Prince and Princess of Wales have embarked on their first visit to the devolved region since their new titles were conferred by the King.

William and Kate are set to journey the length of Wales on Tuesday, starting at Holyhead in Anglesey, North Wales, and then travel to Swansea in South West Wales.

Queen Elizabeth II, the UK's longest-serving monarch, died on September 8 in Scotland after reigning for 70 years. She was 96.

PTI