As King Charles III waved and smiled to wellwishers outside of hospital last week, he projected an aura of strength and stability.
With Queen Camilla by his side, the pair were met with cheering crowds as they left a private clinic in London after the king's surgery for a benign prostate enlargement.
The singularly British display of keeping calm and carrying on might have held no other meaning beyond a choreographed exit following a hospital stay.
But it has taken on greater significance after a dramatic start to 2024 for the House of Windsor.
In separate statements last month the monarch and his daughter-in-law, Princess Kate, announced they would need time off to recuperate from medical procedures.
Sarah Ferguson, the Duchess of York, then announced she had been diagnosed with malignant melanoma, an aggressive skin cancer.
In Charles's case, the monarch is noted for being remarkably healthy, enjoying long rambles in his garden and sticking to a daily exercise regime.
His procedure last month was the first time he had been in hospital since he broke his arm in the 1990s.
Despite his age and short hospital stay, the expectation was that the noted "workaholic" would recover and return to his duties as soon as possible.
But a week after his release came the shocking news he had been diagnosed with cancer.
Instead of returning to full-time work, Charles will now step back from public-facing commitments while he undergoes treatment, which has already started.
"Regrettably, a number of the king's forthcoming public engagements will have to be rearranged or postponed," the palace announced.
While there is a degree of discretion around the king's condition, and it is not known what type of cancer he has been diagnosed with, the palace says he will continue to perform his constitutional role as head of state.
"He's the king, he's got to put on a show and he's been doing it all his life," editor-in-chief of Majesty Magazine Ingrid Seward told Reuters.
But if Charles did need help, there is a unique circle of advisors — counsellors of state — he could count on, who are constitutionally empowered to step in if he were to become seriously ill.
Among that small group are Prince Andrew and Prince Harry, though both no longer count as working royals.
In 2022, Charles expanded these counsellors to include his sister, Princess Anne, and younger brother, Prince Edward, allowing him to pull from a greater pool of people should he need it.
The move may have foreshadowed this exact scenario, saving him from potentially awkward speculation about whether Harry and Andrew could step in while he recovers.
A small circle of royals as backup
As the UK's head of state, the king serves as the figurehead for the United Kingdom and the Commonwealth.
Though most of his powers are symbolic, he also performs several key functions, including giving royal assent to bills passed in parliament, appointing new prime ministers and ministers, and opening new sessions of parliament as well as dissolving them before an election.
He also holds a regular audience with the prime minister and receives daily briefings from the government.
Buckingham Palace has sought to assure the public his leave of absence will include his "public-facing duties", but that he will continue to "undertake State business and official paperwork".
But if the king were to become severely ill, he could still call upon that constitutionally appointed support system, his counsellors, to exercise royal functions.
"There's no sort of threshold of illness or anything. So it is in practice, I think it's the king's decision for counsellors of state … It can all be very flexible," Craig Prescott, a constitutional law lecturer at Royal Holloway, University of London, told Canadian news outlet CBC.
The Regency Act 1937 states that counsellors include the spouse of the monarch and the first four members of the royal family in the line of succession, who are of full age and call the UK home.
When Charles became king that included Camilla, Prince William, Prince Andrew, Prince Harry and Princess Beatrice.
Under ordinary circumstances where Camilla was travelling with her husband, it would have left the king with just one counsellor to carry out his duties given Andrew and Harry had stepped back from their roles. Beatrice is not a working royal.
Hence Charles's decision to amend the Counsellors of State Act in 2022 and add Edward and Anne.
In a statement announcing the updated legislation, the leader of the House of Lords also clarified that only "working royals" could carry out the role of counsellor of state — effectively excluding both Harry and Andrew.
"The elegance of this solution is that it does not remove anyone from the pool of potential counsellors," writes Dr Prescott.
"…. Although there is a principled argument for [Andrew and Harry's] removal, it is legally unnecessary. There will still be only three active counsellors."
At this stage, Buckingham Palace says it does not expect the counsellors of state will be necessary, but the move has solved what could have been a potentially tricky problem for Charles.
William may need to step up
Like his father did as Queen Elizabeth's health failed, Prince William will likely have to step up in the next few weeks as Charles recovers.
The BBC reports he will now be expected to play a bigger role in terms of public appearances and covering for official duties.
It comes at a troubling time for the next in line to the throne, who has been supporting his wife as she has grappled with her health issue.
The pair had taken a step back from public duties in recent weeks after the Princess of Wales had abdominal surgery for an undisclosed condition.
While Catherine will not resume her duties until after Easter, all eyes will be on William this week as he returns to work on Wednesday to attend London's Air Ambulance Charity Gala Dinner.
There is little doubt it will be a challenging time for the prince both personally and publicly.
"I ... feel like the pressure on William has never been greater because his wife is not able to participate, he has three children he's kind of helping look after, as he should, and then now, he has to kind of carry the weight [of his father]," royal observer Rachel Bowie, who co-hosts the Royally Obsessed podcast, told USA TODAY.
Some senior royals are already stepping up, continuing to perform their public roles to keep the royal diary ticking over.
Among them is Camilla who has kept up a regular schedule of events despite her husband's health scare.
Along with appearances at events in London and Cambridge last week, she joined celebrations for the 850th anniversary of UK charity St John's Foundation in Bath, where she had told wellwishers her husband was "recovering well".
It is understood she will continue with her full programme of public duties as Charles recovers.
Princess Anne has also maintained her schedule of public events, travelling to the Gordonstoun School in Scotland last week for an event that honoured the legacy of her late mother and father.
All eyes on Harry
As for the king's second son, the Duke of Sussex touched down in London overnight just 24 hours after the cancer diagnosis was made public.
Harry's role will be limited to supporting the king, and will not extend to stepping into his father's shoes, since he remains a counsellor of state in name only.
The prince has done what many other sons would do if a family member was ill, but his return is notable amid a royal rift.
His relationship with senior members of his family, particularly his father and brother, has been strained since he stepped back from royal duties and moved to America in 2020.
Along with failing to return his calls, Harry said the king had begged him and his brother not to "make his final years a misery" following Prince Philip's funeral.
But it does appear there have been some efforts to repair the relationship, with Harry appearing at his father's coronation last year and calling his father on his 75th birthday.
The king reportedly broke the news of his diagnosis to both William and Harry personally. Shortly after arriving in London, Harry spent 45 minutes at his father's residence in Clarence House.
The monarch's health situation has prompted suggestions this might be an opportunity for the two brothers to get together and patch up their differences.
"This could be a moment of rapprochement within the royal family and that would be wonderful," says University of Sydney royal historian Cindy McCreery.
After years of division, Charles's diagnosis may act as a leveller for the heir and the spare as they come together to support their father in a time of need.