Princess Beatrice will be able stand in for the monarch after becoming a counsellor of state following the Queen's death. She joins Prince Andrew, the Duke of York, along with the King's two sons, Prince William and Prince Harry.
Where King Charles cannot carry out his official duties temporarily because of illness or absence abroad, then two or more of them can act in his place. Before the Queen died, Charles, William, Harry and Andrew held the position, because they were the top four people in the line of succession over the age of 21.
But now Charles is King, Beatrice joins her father as number four on the list, not including Queen Camilla who can also act in his absence as his spouse.
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In her new role, Beatrice will be authorised to carry out many of the official duties of the sovereign, according to the Royal Family website.
This includes attending Privy Council meetings, signing routine documents and receiving the credentials of new ambassadors to the United Kingdom. They are given the authority where necessary via Letters Patents issued by King Charles III.
Beatrice remains only ninth in line to the throne, and Edoardo Mapelli Mozzi in 2020 and has a daughter, Sienna, who is almost one year old.
The 34-year-old not a full-time working member of the royal family and holds a job at a data and software company.
In reality, Beatrice may be second in line if duties are needed, as Prince Harry lives in the US, and the Duke of York was stood down from official duties after the Virginia Giuffre sex-abuse scandal.
He denied all allegations against him and later settled the civil case for an undisclosed sum.
While it is uncommon for counsellors of state to be required, it happened in May when Prince Charles and Prince William deputised for the Queen at the state opening of parliament.
Discussing the possibility that a situation could occur where Prince Andrew was the only person available to act alongside Prince William, Dr Craig Prescott, an expert in constitutional law, told the Telegraph: "I imagine in practice they would co-ordinate their diaries as much as possible so the situation doesn't arise."
The Queen was a staunch supporter of her son, but with the loss of his mother, Andrew looks set to remain in the royal wilderness.
Royal author Robert Jobson says that Prince William had, unlike Charles, previously cut off all contact with his uncle.
"There will be no public role or comeback for York, if the Duke of Cambridge has any input on the matter – and let me assure you, he does,” a source told Jobson.
"He should be banished, as far as Prince William is concerned.”
