When Prince William becomes king, there may be fewer royal working members to work with, as most senior royals are currently over 70 years old.
A constitutional expert said Prince William may need to appoint non-royal members as secretary of state during his tenure because he will likely not be able to count on the company's large number of senior members for decades. Dr. Craig Prescott, author and lecturer in law at Bangor University, considered possible solutions that King William and Queen Catherine might have to choose after he ascended the throne, because there would be enough state advisers—people who could replace him and Catherine to perform constitutional duties on his behalf when he was ill or away from the country.
Referring to the debate on the Secretary of State bill, which took place on Monday for its second reading in the House of Lords, the expert told Express.co.uk: "The debate in the House of Lords on Monday was interesting because it really started to look longer into the future.
Perhaps in 20 years or so, we may have a much smaller royal family focused on William and Catherine as kings and queens, and their children, supported by Prince Edward. At this time, Princess Anne will be in her 90s.
"At some stage, we may need to think about a different approach. It may be that we allow the heir to the throne to act alone, at least in some functions.
"There are precedents such as at the end of Queen Victoria's reign, when the Prince of Wales (later Edward VII) convened a meeting of the Privy Council on her behalf when she was abroad.
Another possibility is to include non-members of the royal family in the list of state councilors, perhaps acting in conjunction with members of the royal family.
"This could involve retired Supreme Court justices who are as politically neutral as the royal family."
"Again, there is precedent that before the Regency Act was first passed in 1937, state councilors were sometimes not members of the royal family. For example, in 1911, he served as counsellor to the State with Prince Arthur of Connaught, the Archbishop of Canterbury, the President of the Privy Council, and the Chancellor.
"In the long run, without royalty, we may have to think about these issues." But this may be something in the future, and there is no need to think about this just before that.
King Charles can currently count on the company to have 10 full-time employees, six of whom are over 70 years old.
Given the advanced age of many high-ranking royals and the fact that both Prince Harry and Prince Andrew no longer perform public office, William may only count his wife Kate, his three children – Prince George, Princess Charlotte and Prince Louis – and the Earl and Countess of Wessex as senior royals over the course of decades.
That could pose problems if the royal family follows through on the plan announced Monday not to enlist any non-working members of the company as state advisers.
Currently, the Regent Laws of 1937 and 1953 set out who is eligible to be elected Secretary of State, which stipulates that the monarch's spouse and the next four heirs who reach the age of 21 – regardless of their status in the domestic company – can be chosen by the monarch as a stand-in.
At least two advisers need to be appointed to perform constitutional duties on behalf of the monarch.
However, Parliament is debating a new bill that would add potential advisers available to King Charles, Princess Anne and Prince Edward.
Buckingham Palace informed the House of Lords through Lord Tru, Lord Keeper of the Seals, that while the new bill did not exclude current non-working royals, who were also advisers – Prince Harry, Prince Andrew and Princess Beatrice – "in fact, working members of the Royal Family – I repeat – will be required to serve as State advisers and diaries will be arranged to make them practical".
However, Lord Berkeley, a Labour MP, introduced an amendment on Monday proposing that the Dukes of York and Sussex, as well as "any other person whom the Lord Chancellor considers have not regularly performed their royal duties in the previous two years", should be excluded from the stand-in role for the sake of transparency.
Commenting on the amendment, Dr Prescott said: "From a purely legal point of view, there is little benefit in removing Prince Harry and/or Prince Andrew.
"Even if they are removed from office and no one else is appointed, we will actually have Prince William, Prince Edward and Princess Anne on active duty as state advisers."
"If Buckingham Palace posted a notice on their website stating that only those performing public duties could serve as Secretary of State, then essentially the same effect could be achieved and the issue of transparency could be addressed."