Regular stamps with the Queen’s image will remain valid until the end of January 2023.
“Following the passing of HM Queen Elizabeth II, Royal Mail has confirmed that stamps bearing the image of Her Majesty Queen Elizabeth II remain valid for use,” a Royal Mail statement begins.
“These include definitive stamps – regular ‘everyday’ stamps – and special stamps.”
It continues: “As previously announced, following the introduction of barcodes to everyday stamps, these stamps remain valid until the end of January 2023.
“All special stamps that have already been announced will be issued, although the launch dates of some may change.”
The statement added that Royal Mail post boxes would remain the same.
“In line with past practice, following the death of a monarch all existing post boxes will remain unchanged,” it adds.
“Post boxes already in production or being prepared for installation will also retain the insignia of Queen Elizabeth II.”
Royal Mail said that a gallery of stamps featuring the Queen is available on its website.
The statement added: “No further announcements on stamps will be made before the funeral, and then only at the appropriate time, after consultation with Buckingham Palace.”
The new King will eventually feature on British stamps, and others around the Commonwealth.
He may have already sat for such sculptures or portraits, and he will again have to approve the designs.
For her first stamps as monarch, the Queen was photographed by Dorothy Wilding three weeks after acceding to the throne and again around two months later, finally approving the image in May 1952.
This portrait from 1952 was replaced in 1967 by the famous sculptured head by Arnold Machin, accompanied by the tiny cameo silhouette of the Queen.
Elsewhere, the Royal Mint said it was unable to provide new information on the possible production of new coins, however.
It issued a statement on Thursday in which Anne Jessopp, chief executive officer at the Royal Mint, said: “On behalf of everyone at the Royal Mint, I would like to extend our heartfelt sympathy to the Royal Family at this extraordinarily sad time.
“Queen Elizabeth II ruled with heart and devotion, and will be dearly missed by all of us at the Royal Mint and by millions of people around the world.
“The Royal Mint worked with Her Late Majesty throughout her reign – detailing her journey from new Queen to respected head of state across five coin portraits, and ensuring each new UK coin received her personal seal of approval.
“The remarkable legacy of Britain’s longest serving monarch will live on for many years to come.”
Current Royal Mint coins and Bank of England banknotes remain legal tender.
The Bank of England said a further announcement regarding existing Bank of England banknotes will be made once the period of mourning has been observed.
Additional reporting by PA