Current postboxes in the United Kingdom look like this:

Adrian Cable / Hazelwood Hall Postbox / CC BY-SA 2.0

With the "ER II". What will any new ones have on them when Charles is king - will it be CR III?

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    I think that this question is not primarily about governments, policies and political processes. It's rather about an inconsequential detail of British post boxes. It may be ontopic on history.stackexchange, which have a somewhat broader scope than politics. Commented Jul 25, 2022 at 10:49
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    @Trilarion I don’t see how monarchal succession (and what changes from that) isn’t a political process?
    – Tim
    Commented Jul 25, 2022 at 11:04
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    Not everything is politics just because a monarch is involved. The clothes they wear, the titles they haves, they appearance on stamps or postboxes, I'd say that this is only marginally related to politics. Surely of historical interest but doesn't influence politics really. Just ask yourself, if there would have been other initials there, what would have been the political implication, if there are any? Commented Jul 25, 2022 at 11:22
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    @Trilarion depending on the initials, something or nothing. But in this case, because of the initials, there is a political implication.
    – Tim
    Commented Jul 25, 2022 at 11:28
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    Pointing out that in the U.K. it is common for a King to take a new name during his reign. If Prince Charles were to, for example, take the name, Elvis and become King Elvis (one could debate if he was King Elvis I or King Elvis II ;)), no change in postboxes would be necessary even if they were changed.
    – ohwilleke
    Commented Sep 8, 2022 at 21:56

3 Answers 3


Royal Cypher

The "E II R" is known as the royal cypher. In this case, it stands for "Elizabeth II, Regina".

The design of the royal cypher is not fixed; it doesn't have to take the form of Initial — Regnal Number — Title. They can be a bit more elaborate, such as that of Duke Charles III of Brabant, which used three intertwined Cs (while he was the second Charles to become King of Spain, he was the third Charles to become Duke of Brabant).

the royal monogram of Duke Charles III of Brabant: three red intertwined Cs, not unlike a biohazard symbol, underneath a crown

King Charles III

A few hours after the death of Queen Elizabeth, on the 8th of September 2022, the new King of England has announced that his regnal name will be King Charles III, which puts an end to the speculation (preserved below).

On the 27th of September 2022, his royal cypher was revealed: an intertwined C and R underneath a Tudor crown, with a Roman numeral III in the eye of the R.

A man holding an envelope, showing the royal cypher of King Charles III: an intertwined C and R underneath a Tudor crown, with a Roman numeral III in the eye of the R

Linus Boman offers an in-depth explanation of the design of King Charles III's royal cypher on YouTube.

Also note that current post boxes are not altered; the royal cypher of the current monarch is used on new mail boxes produced during their reign. Over 70 years after his death, some mail boxes bearing King George's royal cypher are still in use today.

What follows is part of my original answer, which was a bit of speculation about the regnal name of the then Prince Charles, prior to the death of Queen Elizabeth.

King Charles

We do not know what regnal name Prince Charles will take when he is crowned King of England. There has been some speculation that, due to negative connotations with the name "King Charles", he might not want to take that name.

Previous Kings Charles

All Kings Charles so far have been Stuarts, while Charles, Prince of Wales, is a Windsor.

King Charles I

King Charles I of England was beheaded for high treason.

King Charles II

King Charles II of England was known for his mistresses and bastard children. About him it was written

Restless he rolls from whore to whore
A merry monarch, scandalous and poor.

King Charles III

Bonnie Prince Charlie, had he succeeded in claiming the throne, would've been King Charles III.

Other Options

Prince Charles was christened Charles Philip Arthur George, so he has other names to choose from.

King George

Prince Charles has denied planning to reign as King George VII:

Officially the Prince's office said yesterday: "No decision has been made and it will be made at the time."

"Charles denies planning to reign as King George", The Guardian, 27 December 2005

Which does not state that he will not do so, but just that he is not planning on doing so.

King Arthur

Choosing to become King Arthur would probably be seen as having illusions of grandeur, due to the legacy of that name.

King Philip

King Philip II was a Spanish king who became King of England through his marriage with Queen Mary I. After her death, he waged war on England, a planned invasion failing after much of the Spanish fleet was destroyed. Again a name with some negative connotations.


I think it's safe to assume that of all options, choosing to be King Arthur would be received worst.

So it could become "C III R" for King Charles III, "P I R" or simply "P R" for King Phillip (I) or "G VII R" for King George VII.

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    @T.E.D. I don't think he cares much about hurt feelings in the colonies.
    – SQB
    Commented May 18, 2017 at 15:07
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    Wow, the royal cipher of King Charles II of Spain has not aged well; at first glance I thought it was the biohazard symbol.
    – KRyan
    Commented May 18, 2017 at 15:23
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    Nobody's feelings would be hurt. Its just really bad PR. It'd be like Burger King naming a new sandwich after a disease. Its entirely their business, but they shouldn't be shocked when a lot of people are reluctant to eat it.
    – T.E.D.
    Commented May 18, 2017 at 15:29
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    @T.E.D. Elizabeth’s father ruled as King George (VI), and it wasn’t much of an issue that I can tell. Not sure why we Americans should or would care.
    – KRyan
    Commented May 18, 2017 at 17:29
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    @T.E.D. This came up when the young Prince George was born and the consensus seemed to be that nobody in the US much cared. There have been no campaigns to rename Georgia or Georgetown, at least none that I am aware of.
    – phoog
    Commented May 19, 2017 at 13:52

The cypher of King Charles III has been announced.

It features his initial C, for Charles, R, for Rex, the Latin for King, and the Roman numeral 3.

It has a Tudor Crown above the letters. There is a separate Scottish cypher which uses the Scottish Crown instead.

Cypher of King Charles III, described above

As per BBC:

The monogram combines his initial "C" and "R" for Rex, the Latin for king, plus III for the third King Charles.

It was personally chosen by the King, from a range of designs produced by the College of Arms.

… there won't be a sudden change on post boxes … 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.

King Charles: New royal cypher revealed


That symbol, the royal cypher stands for Elizabeth II Regina. This is the made up of the monarch's regnal name, including a regnal number if necessary, and the latin word for king (rex) or queen (regina). A suggestion made by Winston Churchill at the accession of Queen Elizabeth II was that where the numberings differ between England and Scotland the higher be used in both countries, although I'm not sure that there's actually legislation about that. It's even less clear what would happen in the event of Scottish independence.

While Elizabeth II used the first of her given names as her regnal name, there's certainly no reason she had to. For example, her father George VI was christened Albert Frederick Arthur George. So if Charles accedes to the throne he might choose to do so, and thus be Charles III, he might also pick another name. One mischievous suggestion is that he might choose another of his middle names, and rule as King Arthur.

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    That's an interesting point about Scotland- I know king James was both VI and I - and is referred to as "King James VI and I". Would Scotland keep the British monarchy or get a new one if they left the union?
    – Tim
    Commented May 18, 2017 at 11:24
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    If Scotland becomes independent, then its choice of Head of State would be decided by the Scottish government, however that ended up being organised. The Scots could easily choose to keep continuity with the previous crown of Scotland, which came into personal union with the crown of England with James VI and I. This would mean the current British monarch would become monarchy of the new Kingdom of Scotland. They would then be free to have different rules of succession though, which was actually one of the issues behind the Acts of Union back in the 18th Century.
    – origimbo
    Commented May 18, 2017 at 12:23
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    Given the general decline in the volume of snail-mail, the question might be academic so far as "new post boxes" are concerned (there might not be any!) - but the royal cypher is used for other things, of course.
    – alephzero
    Commented May 18, 2017 at 14:40
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    @alephzero I assume that if one needed replacing due to damage it would have a new cypher. In addition, large new estates are being built - at least where I live. Hopefully they will have postboxes within them!
    – Tim
    Commented May 18, 2017 at 16:16
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    Charles is not limited to his own name in picking a regnal name. While most British monarchs have reigned under one of their baptismal names, Robert III of Scotland was John Stewart before he assumed the throne. Commented May 18, 2017 at 21:45

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