The King’s monogram – which appears on government buildings and post boxes in Britain and Commonwealth nations – has been revealed.

The cypher, selected by the new monarch from a series of designs prepared by the College of Arms, consists of the initials ‘C’ and ‘R’ – representing Charles’s name and “Rex”, the Latin for king – alongside a depiction of the crown.

A version used in Scotland will feature the Scottish Crown.

It will eventually replace the “EIIR” stamp of the late Queen, who died earlier this month after 70 years on the throne.

“The decision to replace cyphers will be at the discretion of individual organisations and the process will be gradual,” Buckingham Palace said in a statement.

The Court Post Office at the palace will frank its first items of mail using the new cypher on Tuesday.

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Elsewhere, the makers of Britain’s currency and stamps have said they will begin the slow process of switching from using an image of the late Queen to the new monarch.

“The first coins bearing the effigy of His Majesty King Charles III will enter circulation in line with demand from banks and post offices,” Royal Mint chief Anne Jessopp said.

“This means the coinage of King Charles III and Queen Elizabeth II will co-circulate in the UK for many years to come.”

The replacement process will take some time with the Royal Mint estimating there are some 27 billion coins bearing an effigy of the late Queen.

The Bank of England said banknotes with a portrait of the King would enter circulation by the middle of 2024. Images of updated notes are expected to be revealed by the end of the year.

The Royal Mail said the current picture of the late Queen used on “everyday” stamps would be updated to feature an image of her son. The new stamps will enter circulation only once current stocks are exhausted.

All existing currency and stamps bearing the late Queen’s image will remain valid.

The announcements came as other British royals and their households returned to official duties as the period of official mourning in memory of the late Queen ends.

The royal family has carried out official duties only where appropriate since the Queen’s death on September 8 and its members have dressed in black as a mark of respect when in public.

They will carry out their normal official roles in full from Tuesday, a week after the late monarch’s funeral at Westminster Abbey.

In one of the first announced, the Prince and Princess of Wales will visit Wales for the first time since taking up their titles.

The royal couple had promised to visit at the earliest opportunity following the death of the Queen, saying they hoped to keep “deepening the trust and respect” they have with the people of Wales.

The pair’s last official visit to Wales was as Duke and Duchess of Cambridge to Cardiff Castle in June, for rehearsals for the platinum jubilee concert.

They also lived on Anglesey for three years immediately after their 2010 wedding. They will return to the Welsh island on Tuesday, with a visit to a lifeboat station.

Late last week, Prince William and wife Kate Middleton held an afternoon tea at Windsor Castle to thank those involved in helping to organise the Queen’s funeral.

The King carried out one official engagement during royal mourning – a telephone audience with British Chancellor Kwasi Kwarteng on Thursday on the eve of his tax-cutting mini-budget.

He and the Queen Consort travelled to Scotland after last week’s state funeral. It is expected the monarch might remain at his home of Birkhall, on the Balmoral estate, into early October, following the tradition set by the late monarch.

The Queen would normally spend 10 weeks at her Scottish home during summer, returning to London as the autumn session of Parliament began.

Planning is under way for the King’s coronation, which is expected to be held next year.

-with AAP