Prince Philip, 96, was forced to pull out of a rare public appearance this week, because, the palace said, he was feeling slightly “under the weather.”

With a particularly vicious flu virus doing the rounds this spring, Philip’s non-appearance set off a now-familiar round of speculation and panicked obituary preparation in the newsrooms of national newspapers.

“ Charles is already being handed ever increasing powers and responsibilities by the queen—and Charles is passing more on to William. ”

The palace was at pains to stress there was no cause for concern, but incidents such as these do serve to focus minds on what will happen when Prince Philip dies, how his death will affect the queen’s ability (and desire) to continue her own high-profile public life, and, ultimately, how the process of succession will be managed.

There is absolutely no question that Prince Charles will be the next king of England. Princess Diana’s hope that the crown would skip a generation and pass directly to William will not come to pass.

Were there any doubt of that, it can be seen in the fact that Charles is already being handed ever increasing powers and responsibilities by the queen—and Charles is passing more on to William.

This week, for example, it was Prince William who conducted an investiture at Buckingham Palace, knighting the former Beatle, Ringo Starr.

The queen, is also lobbying hard for Charles to be declared the next leader of the Commonwealth. A decision on this may be made as soon as next month at the Commonwealth Heads of Government meeting in London.

Charles also attended 546 engagements last year, more than any other royal family member, reflecting his efforts to take on more of the queen’s most grueling day-to-day work, and earning him the title of hardest-working royal.

But as to what exactly the queen’s powers are, that can be hard to define. Walter Bagehot, the great constitutional historian of the 19th century, once claimed that Queen Victoria “could disband the army; she could dismiss all the officers... she could sell off all our ships-of-war and all our naval stores; she could make a peace by the sacrifice of Cornwall and begin a war for the conquest of Brittany. She could make every citizen in the United Kingdom, male or female, a peer; she could make every parish in the United Kingdom a ‘University’; she could dismiss most of the civil servants, and she could pardon all offenders.”

It seems unlikely Queen Elizabeth would get away with even contemplating any one of the above actions without triggering a revolution, but there are certain other jobs she is regularly required to perform to ensure the smooth running of the state; signing government policy into law, the weekly audience with the prime minister, and the appointing and dismissing of prime ministers, for example.

What all of these (admittedly ceremonial) jobs have in common is that they are much easier to perform if you are living in London, or, at a push, nearby Windsor.

If, as many suspect, the queen does intend to retire to Scotland after either the death of her husband or her 95th birthday, it seems likely that she will have to give Charles almost all of her powers, if the spectacle of the prime minister of the day rushing 700 miles north every Wednesday for tea with Her Majesty is to be avoided.

The only two ways to do this are either for the queen to abdicate—which the palace has always briefed is not a conceivable event, due to the muscle memory of the 1936 abdication crisis which came close to toppling the monarchy—or to declare Charles her “regent” and entitled to act in her name.

Robert Jobson, the veteran royal reporter, claimed in an article in the Daily Mail last year that a regency was being planned, reporting that staff at the palace have been ordered to be “‘up to speed’ on the 1937 Regency Act, which grants power to the heir apparent “in the event of the incapacity of the Sovereign through illness, and for the performance of certain of the Royal functions in the name and on behalf of the Sovereign in certain other events.”

“ Prince Regent does not have happy connotations, having last been used during the madness of King George III. I don’t think that mechanism would get dusted off with any keenness at all. ”

However Robert Lacey, the royal author and historical consultant for the Netflix series The Crown told The Daily Beast he thought a regency was an unlikely outcome.

“Prince Regent does not have happy connotations, having last been used during the madness of King George III,” he said. “I don’t think that mechanism would get dusted off with any keenness at all.”

Lacey said his personal suspicion was that if the queen does live to an advanced age, the principal change would be that she would be based at Windsor Castle rather than Buckingham Palace, which would allow her to continue to keep up with her day to day governmental business and weekly audiences.

“Everyone talks about how much Queen Victoria loved Balmoral after Albert’s death, but she was known as the ‘Widow of Windsor’ for good reason. She spent an enormous amount of her time in Windsor and there is no reason the queen could not do the same,” Lacey says, adding that she “shuttles in and out of Windsor a lot more than most people realize.”

So how will any transition period really look?

On the face of it, outsiders would notice few changes, Lacey says. Investitures—as the example of Ringo Starr this week shows—are rarely conducted by Her Majesty any longer. The significant winding down of her public appearance schedule would be the most visible change.

One vivid example of Charles’ power, and the queen’s willingness to let him have it, can be found in the resignation of her Private Secretary Christopher Geidt last year. The writer Tom Bower has claimed in his explosive biography of Charles that Geidt was given the boot at Charles’ request.

Bower writes that when Charles “insisted on taking over more of his mother’s public duties” he assumed the chief obstacle would be be Geidt, “so he went to the Queen to demand her private secretary's resignation. Very reluctantly, the Queen agreed.”

The writer Christopher Andersen, author of The New York Times bestseller Diana’s Boys, is one of the few voices who claim the queen will abdicate. He thinks a regency will not happen but for different reasons to Lacey—that it doesn’t go far enough.

“ When Prince Philip dies or the Queen turns 95, whichever comes first, I believe the Queen will abdicate—the Palace will spin it as a retirement, but technically it will be an abdication—leaving Charles to become king while still in his early 70’s. ”

“Being regent is far from being king, and the Queen knows that it would be nothing more than a temporary fix, and not a particularly pleasant one for her son,” he tells The Daily Beast.

“When Prince Philip dies or the Queen turns 95, whichever comes first, I believe the Queen will abdicate—the Palace will spin it as a retirement, but technically it will be an abdication—leaving Charles to become king while still in his early 70’s.

“He’ll still be the oldest person ever to ascend to the throne, which is far from ideal since polls have always shown most Britons want William and Kate to be their next king and queen.

“It could be a two-step process, with the Queen allowing a regency, and waiting a few years to abdicate. But again, that just complicates matters. Charles would grow restless awfully fast in the role of regent. He has been waiting his whole life for the Big Job, after all. At this late stage, it would be a little cruel to make him audition for the part. His whole life has been an audition.”