All UK kings and queens since the postbox was introduced in 1852 have had their royal cipher displayed on postboxes installed during their reign. But getting a postbox ready for a new monarch is not always straightforward! Edward VIII boxes were still being installed in early 1937, and then his father George V’s cipher had to be reused on new boxes until George VI’s was ready. In 1952 it took until November before the first new EIIR box was unveiled in Whitehall, London. Royal Mail will use up their existing stock of Elizabeth II boxes before starting on Charles III’s.

Charles III’s new cipher has been revealed, with a special version for Scotland – since 1953 Scotland and the rest of the UK have had different ciphers, showing the Scottish crown north of the border. The newest postboxes are made of stainless steel and only need a small part to be redesigned before being bolted on to the box, so it should not take long to start production. We don’t know when the first Charles III boxes will be installed, but we’re sure there will be a big announcement, and they will probably appear in the four UK capitals – Belfast, Cardiff, Edinburgh and London.