The first letters to be stamped with the King’s cypher have rolled off the franking machine at Buckingham Palace.

Charles requested the inaugural batch of envelopes to be franked, and the Palace’s Court Post Office has produced an initial run, expected to increase in the weeks ahead.

It is understood messages of appreciation, for the cards and letters of condolence received by the royal family following the Queen’s death, will begin to be sent out later this week.

David White, Garter King of Arms, the senior herald at the College of Arms which produced the image of the new King’s monogram, said the cypher is likely to become a familiar image to the public.

In his role as Garter King of Arms, Mr White read the proclamation declaring the new King from a balcony at St James’s Palace, following the Queen’s death.

He said about the cypher: “It’s the very personal mark of the sovereign and whereas the royal arms don’t necessarily change from reign to reign, the cypher does.

“I think it will become very familiar, I imagine most people are familiar with the previous cypher – the late Queen’s EIIR – without really realising it.”

Tim Noad, heraldic artist and calligrapher at the College of Arms in London, created 10 designs that were put before the King, who chose his preferred monogram.

He also designed the Queen’s Golden, Diamond and Platinum Jubilee Medals and created the elaborate and intricately penned “instrument of consent” from the Queen that formally approved the marriage of William and Kate, now the Prince and Princess of Wales, in 2011.

The cypher features the King’s initial C intertwined with the letter R for Rex – Latin for king – with III within the R denoting Charles III, with the crown above the letters.

The monogram is Charles’s personal property and a Scottish version features the Scottish Crown, and was approved by Lord Lyon King of Arms.

It will appear on government buildings, state documents and on some post boxes in the coming months and years, with the decision to replace cyphers at the discretion of individual organisations.