The cypher of King Charles III has been revealed, showing an image to be used by government departments and on state documents and post boxes.
It was personally chosen by the King, from a range of designs produced by the College of Arms.
The monogram combines his initial "C" and "R" for Rex, the Latin for king, plus III for the third King Charles.
The cypher, a visual identity for the new reign, replaces the E II R of Queen Elizabeth II.
There will be other changes ahead to mark the new reign of King Charles:
- The Bank of England says new bank notes featuring King Charles III are "expected to enter circulation by mid-2024", with the image to be revealed before the end of this year
- New coins will be produced, says the Royal Mint, but without any date yet given - but will appear "in line with demand from banks and post offices"
- Existing banknotes and coins will continue to be valid, with Charles and Elizabeth notes and coins being used alongside each other
- The Royal Mail says that new stamps featuring King Charles will "enter circulation once current stocks of stamps are exhausted"
But a set of four memorial stamps are to be released in November, showing portraits of Queen Elizabeth II taken at different stages during her reign.
As the period of royal mourning ends, the new cypher of King Charles will be used for the first time.
Its first application will be in the Buckingham Palace post room on Tuesday, with the cypher used to frank letters from the Royal Households.
There is a separate version of the cypher for Scotland, which features the Scottish Crown.
But there won't be a sudden change on post boxes or on public buildings.
There are still post boxes in use from the reign of Queen Victoria, Edward VII, George V and VI, and the original cyphers remain until boxes need to be replaced.
Almost 70,000 of the current post boxes, about 60% of the total, date from the reign of Queen Elizabeth II. There are only about 170 surviving from the short reign of Edward VIII, who abdicated in 1936.
Boxes already under construction or ready for installation will continue to have the late Queen's cypher, Royal Mail says.
Where royal cyphers appear on buildings, it will be up to individual organisations to decide when or if they will be updated.