Princess Elizabeth was deep in the Kenyan forest on the adventure of a lifetime, spotting wildlife from high up in the treetops, when her father died and she became queen.

The world awoke on February 6, 1952, to the death of King George VI, who had succumbed during the night to lung cancer at the royal Sandringham residence in Norfolk.

His 25-year-old daughter and heir to the throne only heard the news later the same day, when word reached Elizabeth thousands of miles from home in the wilderness of the Aberdare Range.

Kenya, then a British colony, was the first stop on Elizabeth's tour of the Commonwealth she had embarked upon with her husband, Prince Philip, in place of her ill father.

The royal couple had taken a night out of their official engagements to stay at a one-of-a-kind game-watching lodge perched in a tree in the Aberdares interior.

It was during their night at the Treetops hotel that the king would die, and Elizabeth would become queen.

Jim Corbett, the naturalist and hunter who accompanied the royal couple to Treetops, is credited with writing in the visitor book: "For the first time in the history of the world, a young girl climbed into a tree one day a Princess and, after having what she described as her most thrilling experience, she climbed down from the tree next day a queen."

- 'Most wonderful experience' -
In fact, the Duke of Edinburgh broke the news to Elizabeth after they had left Treetops but the story stuck and the hotel became the fabled locale where a princess became a queen.

First opened in 1932 as an overnight stay for wealthy and intrepid visitors, Treetops overlooked a watering hole from its position in a giant fig tree.

In its day, there wasn't really anything like it. 

A private setting among branches, remote in the African bush, Treetops offered the privileged elite a chance to encounter wildlife up close, and in safety, as they grazed below.

Elizabeth and Philip kept a handwritten tally of what they saw, recorded on a sheet of paper framed still today inside Treetops.

Large herds of elephant -- "about 40" in one sighting -- were spotted at the watering hole, along with baboons and waterbuck.

"Rhinos all night", read the list dated February 5/6, 1952 and signed by the Princess and Prince, and "in the morning, two bulls fighting".

An aide to the royal couple, instructed to write and thank the hotel's owners, described a "tremendous experience of watching the wild game in its natural surroundings" and day and night "packed with interest".

"I am quite certain that this is one of the most wonderful experiences that either The Queen or The Duke of Edinburgh have ever had," read the letter framed in Treetops dated February 8, 1952.

- Faded memories -
Two years after the historic visit, with Elizabeth having assumed the throne, Treetops burned down in what was rumoured to be an arson attack by anti-colonial Mau Mau rebels.

A new, much larger hotel was built on elevated wooden stilts on the opposite side of the watering hole to the original setting, where it still stands today.

The royal visit -- and the legend to go with it -- made Treetops among the most famous hotels in the world.

Well-heeled guests could stay in the Princess Elizabeth Suite, peruse royal memorabilia in the dining room, or gaze upon a portrait of the Queen framed by the tusks of an elephant shot by hunters in the 1960s.

Elizabeth and Philip returned in 1983 -- more formal than safari, with the queen in a knee-length dress, the duke in a blazer and tie -- to find Treetops very much changed in the 31 years between visits.

For many years, nothing more than a plaque marked where they spent that fateful night by the watering hole.

But today it is nowhere to be seen, put in storage after Treetops closed its doors at the onset of the coronavirus pandemic.

Two years later -- as the queen prepares to mark her platinum Jubilee -- it remains shut, a faded icon of a bygone era.

Queen Elizabeth II to mark 70 years on the throne
Queen Elizabeth II on Sunday becomes the first British monarch to reign for 70 years, heralding the start of her Platinum Jubilee year despite her retreat from public view.

But the landmark date this weekend will see little fanfare, as the 95-year-old monarch traditionally spends the anniversary of the death of her father in private.

The sovereign's record-breaking reign as head of state began when she was aged 25 and watching wildlife in a remote part of Kenya with her husband, Prince Philip.

She has since become the one constant in an era of rapid social and political change, a figurehead of modern Britain and a living link to its post-war and imperial past.

The Queen -- who regularly tops surveys as the most popular royal -- on January 23 flew by helicopter to her sprawling Sandringham estate in eastern England.

She had been due to stay at Sandringham House with close family over Christmas and the New Year but the annual visit was postponed because of surging cases of Omicron.

No public engagements are expected on Sunday, in keeping with previous years.

But four days of festivities are planned for early June, including a military parade and a music concert, street parties, a mass attendance picnic and a "Platinum Pudding Competition".

Commemorative coins have been minted to mark the unprecedented milestone.

- Retreat -
At Sandringham, the queen is staying at Wood Farm, a five-bedroom cottage that was favoured by her late husband after he retired from public life in 2017.

According to British media, Prince Philip spent his time there reading, painting and walking, in more modest surroundings away from liveried servants and royal pomp.

The queen travelled to Sandringham by helicopter and was photographed in the back of a Range Rover, wearing a silk headscarf printed with birds.

The 20,000-acre (8,100-hectare) estate, near the north Norfolk coast, is dear to her heart.

Not only was it a retreat for Philip until he joined her in Covid isolation at Windsor Castle in 2020, but also for her father, George VI, who died there of lung cancer, aged 56.

It was also a favoured residence for her grandfather, King George V, who also died there, and her great-grandmother, Queen Alexandra.

After Philip's death in April last year, the queen returned to public and official engagements, including hosting world leaders at the G7 summit in Cornwall, southwest England.

But she has been forced to slow down on advice from doctors, after an overnight hospital stay in October sparked public concern. 

Since then she has largely stayed at Windsor and made few public appearances.

The last dates back more than a month to her annual -- recorded -- Christmas message, where she paid a rare personal tribute to her husband of 73 years and his "mischievous inquiring twinkle".

- Respite -
Only three monarchs in global history have reigned for more than 70 years.

France's Louis XIV reigned for 72 years, 110 days from 1643 to 1715. Thailand's king Bhumibol Adulyadej was on the throne for 70 years and 126 days from 1946 to 2016.

Johann II, prince of Liechtenstein, ruled for 70 years, 91 days from 1858 to 1929.

Sandringham could give Elizabeth some respite from a scandal involving her second and reportedly favourite son Prince Andrew that has cast a shadow over her jubilee year.

In mid-January, she stripped him of his honorary military titles and charitable positions as he battles a US civil case for sexual assault.

The move effectively removes him from public life, and is designed to insulate the royal family from any damaging revelations and repercussions.

Andrew, 61, vehemently denies the accusation but he has been tainted by his associations with the convicted sex offenders Jeffrey Epstein and Ghislaine Maxwell.