By Lucia Stein and Rebecca Armitage for the ABC*
The plans for her death were meticulous. Her lavish funeral had a code name. Her obituaries were written. Her son and heir was ready.
But when the kingdom's second Elizabethan era drew to a close on 8 September, 2022, everyone suddenly seemed to be a little caught off guard.
The newly sworn-in UK prime minister Liz Truss was still moving her things into Number 10, and she sent aides scrambling to her house to find her a black dress.
Charles, seemingly unaware that he was about to become king, reportedly grabbed a basket and wandered into the woods to clear his head before it had to bear the weight of the crown.
When he realised the gravity of the situation, he made his way back to Balmoral and started to call his loved ones.
Queen Elizabeth II's family members were scattered around the kingdom.
But plans to bring them together to say goodbye to their matriarch and monarch at Balmoral Castle swiftly devolved into arguments.
Charles became locked in a dispute over whether his daughters-in-law, Meghan and Catherine, Princess of Wales, should be included among the mourners.
The Queen's final hours were the end of an era.
But they also foretold the family dynamics that Charles would inherit during his first year on the throne.
This is the inside story of the Queen's last day on Earth - and how it set up the reign of King Charles.
The Queen's final days
In the year leading up to her death, doctors had ordered Queen Elizabeth II to rest and take it easy.
As monarch, her schedule was a busy one, often filled with special events, royal engagements and hosting foreign dignitaries.
But with her health at risk, Queen Elizabeth began to scale back her work, while still performing the official obligations of her role.
In her last public appearance before she died, the monarch appointed her 15th and final prime minister.
The event, which took place in Balmoral, was a break from tradition since the Queen was not well enough to make the trip home. It may have also been an early indication that all was not well.
Leaning on her stick after months of mobility issues, she stood smiling and was said to be in "good spirits" as Liz Truss was ushered in for her meeting.
"She certainly did look more frail than when I photographed her in the summer," PA Media photographer Jane Barlow, who was the last person to publicly photograph the Queen, told the BBC.
"When she came up for Holyrood Week [which takes place at the end of June and beginning of July], at the time they were telling me she would do one, perhaps two engagements, but she did quite a lot that week."
Less than 24 hours later and safely ensconced inside one of her favourite places on Earth, her health appeared to take a turn for the worse.
A virtual privy council meeting related to the appointment of Truss was postponed on the advice of doctors.
And her son and heir was soon alerted to her deteriorating condition, royal biographer Robert Jobson wrote in his book, Our King.
As the sun steadily rose on 7 September, the Queen's helicopter was sent to take the then Prince of Wales from Dumfries House, near Glasgow, back to Balmoral.
He returned and kept vigil with his sister Anne by their mother's bedside.
With no immediate signs of danger, the soon-to-be King decided to take a walk through the woods.
It would be his last as the Prince of Wales.
Mushroom picking, scrambles over flights and an awkward call
Charles took a gentle stroll through the sloping grounds of Birkhall with a walking cane and basket during his mother's final hours, according to Johnson.
The moments of solace he stole between the trees and shrubs, foraging for mushrooms, were a stark contrast to the chaos that was about to unfold.
With the Queen's life ebbing away, difficult conversations were taking place about whether the family should remain in London or fly to see her, a choice that was sure to set off a flurry of speculation about her health in the press.
Meanwhile, Charles and his sons were feuding over whether Catherine and Meghan should accompany their husbands to Scotland.
There had been some confusion at first on whether both of the Sussexes, who had been in Europe for the Invictus Games, would be heading off to see the Queen.
A statement put out by the couple about 2pm suggested both were on their way to Balmoral, but hours later it became clear Harry was alone.
In his memoir, Spare, Prince Harry recalls his father advising him not to bring his wife.
"He told me I was welcome at Balmoral … but without her [Meghan]," he said.
When Harry warned his father not to speak badly about his wife, he says Charles stammered: "He simply didn't want it to fill up with people. Nobody's wife was going, not even Kate, he told me, so Meg shouldn't either."
Catherine was understood to have remained in London with her three children, who were still settling into a new school season. Meghan also stayed behind.
At just after midday, a statement from Buckingham Palace advised the public of the serious nature of the Queen's condition.
"The Queen's doctors are concerned for Her Majesty's health and have recommended she remain under medical supervision. The Queen remains comfortable and at Balmoral," it said.
Charles rushed back from his ramble in the garden to his mother's bedside, while Prince William, Prince Andrew, Prince Edward and his wife, Sophie Wessex, boarded a RAF Northolt jet to Aberdeen airport.
Prince Harry took a separate private jet from Luton airport at 5:30pm, later revealing in his memoir that he discovered his grandmother had died by reading a BBC article on his phone shortly after his plane touched down.
"I spent almost the entire flight looking at the clouds, reliving the last time I'd spoken to my grandmother," he wrote in Spare.
Charles the King
Despite the scramble for flights and cars to get to Balmoral, Queen Elizabeth's end came quickly.
Her death certificate revealed she died just after 3pm on 8 September.
"The Queen more than likely knew that her time was coming to an end, and her family would have been prepared for this too," says associate professor of English at Flinders University, Giselle Bastin.
"As it happens, her health deteriorated even more rapidly than expected."
As one era ended, another was just beginning. But Charles's ascension to the throne occurred against a backdrop of instability.
Europe grappled with war, while Britain was tackling a cost of living crisis, political chaos and the lingering effects of the Covid-19 pandemic.
And on a personal level, the new King's position was tempered by a period of mourning and an acute awareness of the eyes of the world upon him.
There were slip-ups in the early days of his reign, notably a tantrum over a leaky pen during a signing ceremony in Ireland and a controversial meeting with the head of the European Union, Ursula von der Leyen, in February.
British observers noted the awkward timing of the King meeting with a high-profile EU representative just as the UK was finalising its Brexit deal.
But despite having very big shoes to fill, the first year of his reign appears to have gone very smoothly, Dr Bastin says.
He has met with faith leaders across the country, put his personal stamp on his coronation and, for the first time, signalled support for research into the British monarchy's ties to slavery.
"Charles would be keenly aware of what a huge task he has ahead of him, given his mother's tremendous popularity and legacy," she said.
"But he's navigated his new role steadily and has held off implementing any major changes to the running of the royal households or palace protocols."
The task ahead
King Charles's future is not without its challenges.
A key marker of the success of his reign will be his ability to present an image of the monarchy as modern and inclusive amid increasing scrutiny of its colonial past.
Charles's reputation as an advocate and meddler when he was the Prince of Wales may prove easier to overcome.
For the most part, the new King seems to be aware of the need to be more discreet.
"King Charles can't - constitutionally - rock too many boats or meddle in state affairs, but he can exercise influence in aspects of the UK's internal and international affairs," Dr Bastin said.
But underlying family dramas also threaten to overshadow the King's legacy.
In seemingly a step towards his vision of a slimmed-down monarchy model, King Charles reportedly informed several family members, including his brother, that he would be cutting their annual allowances earlier this year.
With many royals economically dependent on him, however, the move sparked a family squabble and a barrage of press.
In an effort to salvage the plan, Prince Andrew was offered the option to downsize and move into Prince Harry and Meghan's vacant Frogmore Cottage, a move which reportedly shocked the couple.
While the pair seem content to remain living in self-imposed exile in America, the ongoing rift between father and son continues to draw headlines and public fascination.
It's a problem that King Charles may need to fix if he is to maintain a House of Windsor that he can pass on to his other son.
* This story was first published by the ABC.