What is a regency, and how would it work if King Charles' health worsens?

Prince William and his father King Charles III (John Stillwell/PA)
With Britain's King Charles being treated for cancer, his ill health has raised questions about whether there could be a need for a regency in the future.
If King Charles was incapacitated, his son William could be appointed Prince Regent through the Regency Act 1937, taking over his duties.
However, British prime minister Rishi Sunak has said Charles' cancer has been âcaught earlyâ, suggesting any prospect of a regency is unlikely at this stage.

If needed, it would be the first time in more than 200 years that the British monarchy has required a regency, with the last Prince Regent being the future George IV.
Here is an explanation of what a regency means, and how and why it would take place:
A period of regency allows King Charles to transfer his powers as monarch to Prince William without having to abdicate.
No. King Charles would still be the monarch and head of state.

But Prince William would be able to perform royal functions in the name of and on behalf of his father.
The Regency Act 1937 states that the monarchâs duties will be performed by a regent if the monarch is declared to be âby reason of infirmity of mind or bodyâ incapable of performing royal functions, or if there is âevidence that the Sovereign is for some definite cause not available for the performance of those functionsâ.

This must be declared in writing by three or more out of the following: the sovereignâs wife the Queen, the Lord Chancellor, the Speaker of the House of Commons, the Lady Chief Justice and the Master of the Rolls.
King Charles has no say and does not need to agree with their decision.
The abdication of the late Queen Elizabethâs uncle â King Edward VIII â in 1936 sparked a major constitutional crisis and the British royal family has never forgotten its devastating impact.

King Charles made a âpromise of lifelong serviceâ in his first address to the nation when he became the monarch.
The British monarchy is also a sacerdotal monarchy â as part of his coronation, King Charles went through a consecration ritual which is similar to the consecration ritual a priest goes through.
You can retire from being an active priest but you are still a priest until you die.
King Edward VIII abdicated before he was crowned.
A regency is a longer-term solution than temporary Counsellors of State.
But Counsellors of State cannot perform certain core constitutional functions, such as Commonwealth matters, the dissolving of parliament, except on the kingâs instruction, creating peers and appointing a prime minister.

King Charles and Prince William jointly performed the state opening of parliament in place of the late queen as Counsellors of State in 2022.
No. It is reversible. If a monarchâs health recovers or they become available to carry out their royal functions, the sovereign can resume their duties.
The last regent was the future King George IV who became Prince Regent through an ad hoc Regency Act in 1811 when his father King George III was declared mentally unfit to be king.

The vain Prince Regent, famously characterised by Hugh Laurie in the sitcom Blackadder III, was known for his heady extravagance, which was a constant source of gossip.
He was an important artistic patron, acquiring an impressive collection of art and patronising architects and designers, and later commissioned the Royal Pavilion in Brighton to be built as his seaside pleasure palace.
He was regent for nine years before becoming king when his father died in 1820.
Yes. Permanent provisions were put in place through the Regency Act passed in 1937 in case a monarch became incapacitated or a sovereign was under the age of 18.
Princess Elizabeth was heir to the throne and only 11 years old in 1937.
Further Regency Acts were also passed in 1943, and later in 1953 to allow her husband Prince Philip to be regent if one was required and her children were under the age of 18.

But future amendments to the legislation may be required because second in line to the throne Prince George is under the age of 18.
Options could include adding Kate to the Regency Act as a potential regent in case anything happened to King Charles and Prince William before George became an adult.
A declaration has to be made to the Privy Council and communicated to the British government.

William would have to take an oath before the Privy Council in which he pledged to be faithful and bear true allegiance to the king, faithfully execute the office of Regent and govern according to law, and preserve the Church of Scotland.
Yes. He would not be allowed to give assent to any Bill which changes the order of the succession to the throne.
He would also not be allowed to repeal or alter an Act made in Scotland entitled âAn Act for Securing the Protestant Religion and Presbyterian Church Governmentâ.
The 1707 Act ensured in pre-Union Parliament of Scotland that the status of the Church of Scotland is not be affected by the Union with England.
No. Constitutional expert Professor Vernon Bognador has said previously it would be up to these countries to make their own arrangements.