As Britain's King Charles III is being treated for cancer, the monarch's state of health has raised questions about what could happen next in case of a worsening situation.
From treatment to diagnosis
The first announcement about the king came Jan. 17 when Buckingham Palace said Charles, 74, would receive a "corrective procedure" at a hospital for an enlarged prostate.
The palace later issued another statement that said he had been admitted to the hospital for a scheduled prostate treatment.
Following a three-night stay at the London Clinic, Charles left the hospital.
But Buckingham Palace announced Monday that Charles has been diagnosed with cancer and has started treatment.
Charles remains "wholly positive" about his treatment and looks forward to returning to full public duty as soon as possible, according to the statement.
"His Majesty has chosen to share his diagnosis to prevent speculation and in the hope it may assist public understanding for all those around the world who are affected by cancer," it added.
If Charles becomes incapacitated?
The ill health of Charles has raised questions about what could be next if his health gets worse.
One scenario could be the Prince of Wales being appointed if Charles was incapacitated, through the Regency Act to take over the king's duties.
But, it is seen as not likely because Prime Minister Rishi Sunak said the king’s cancer has been "caught early," suggesting any prospect of a regency is unlikely at this stage.
What is Regency?
A period of regency allows the sovereign to transfer his powers as monarch to the Prince of Wales without having to abdicate, but it does not mean Prince William would be king as Charles would still be the monarch and head of state.
It would allow William to be able to perform royal duties in the name of and on behalf of his father, Charles.
The case of a Prince regent, through the Regency Act 1937, is not permanent as well and it is reversible. If a king's health improves or he becomes available to carry out royal functions again, the monarch can resume the duties.
The Regency Act 1937 ordered that a regent should perform royal functions if "the Sovereign is by reason of infirmity of mind or body incapable for the time being of performing the royal functions or that they are satisfied by evidence that the Sovereign is for some definite cause not available for the performance of those functions."
Such a decision must be made by at least three: "The wife or husband of the Sovereign", "the Lord Chancellor", "The Speaker of the House of Commons", “The Lord Chief Justice of England," or "The Master of the Rolls."
Charles' ascension, coronation
Charles, formerly known as the Prince of Wales, ascended to the throne following the death of his long-serving mother, Queen Elizabeth II at Balmoral Castle, Scotland on Sept. 8, 2022.
In May 2023, in the first coronation service in nearly 70 years, he was crowned at Westminster Abbey in London.
After he was officially crowned, Charles became the king of the UK and 14 other Commonwealth countries, including Australia, Canada and New Zealand.