The Duchess of Cornwall is reportedly due to step up to a bigger role and could join the top group of royals who carry out duties on behalf of the Queen amid increasing concern over the monarch's health.
On Friday it was revealed the Queen, 95, has cancelled all working visits for the next two weeks and has been advised to stick to rest and stick to “light, desk-based duties”.
Several of her royal engagements have been cancelled, including the COP26 climate change conference which starts in Glasgow today.
The Queen underwent tests in hospital last week and cancelled a two-day trip to Northern Ireland.
Now, palace aides are said to be drafting plans for her daughter-in-law Camilla, 74, to take on a bigger role in The Firm.
Sources claim Camilla, who already carries out a number of royal duties, will be asked to step in and help manage the workload, reports the Mail on Sunday.
Buckingham Palace declined to comment on the claims.
Under current rules, Princes Charles, Andrew, William and Harry are classed as 'Counsellors of State' requiring them to step in if the Queen is unable to perform her duties "due to illness or absence abroad".
By law, Counsellors of State include the next four people in the line of succession who are over the age of 21 but due to recent shifts in the family, Camilla may have to step up.
Andrew retired from royal service last year as he continues to fight sex abuse claims.
Prince Harry now lives in the United States meaning he can no longer undertake the role of counsellor, claims Vernon Bogdanor, the author of Monarchy And The Constitution and professor of government at King’s College London.
A source close to the Palace told the Mail: "This is a constitutional headache. With an ageing monarch there are talks about what will happen if the Queen is unable to work for some reason. You can’t have Andrew and Harry do it and Charles and William are extremely busy."
Dr Craig Prescott, a constitutional expert at Bangor University, said: "The Counsellors of State are a Plan B from a constitutional point of view, but what happens when Plan B isn’t quite ideal? The Queen may look to add the Duchess of Cornwall, who would become a Counsellor of State when Charles is King anyway. Or they could go down the line to Princesses Beatrice or Eugenie, or add more members of the family, like Princess Anne or Prince Edward to the list."
It comes after Buckingham Palace announced the Queen will "rest for at least the next two weeks."
The statement added: "The doctors have advised that Her Majesty can continue to undertake light, desk-based duties during this time, including some virtual audiences, but not to undertake any official visits.
"Her Majesty regrets that this means she will be unable to attend the Festival of Remembrance on Saturday, November 13.
"However, it remains The Queen's firm intention to be present for the National Service of Remembrance on Remembrance Sunday, on November 14."
On Saturday, Prime Minister Boris Johnson insisted the Queen is on “very good form” and it's understood he spoke to the monarch as part of his normal weekly audience.
The Queen has told her family she will host Christmas at Sandringham after she has rested up on the advice of royal doctors.
