At the age of 25, the princess had been standing in for her father George VI on a long-planned international tour that would also reach Australia and New Zealand, accompanied by her husband of five years, Prince Philip.

The 56-year-old king had been thousands of miles away in Sandringham after being too ill from lung cancer to travel.

The couple had been enjoying a brief respite from their royal duties relaxing at a game-viewing lodge, the Treetops Hotel, located in the heart of Kenya, when their lives changed forever.

How did Princess Elizabeth find out she had become Queen?

On 5 February, Elizabeth had spent the day taking cine films of elephants at a nearby watering hole before spending the night in a cabin high up in the trees with the Duke of Edinburgh.

It was there, in her sleep, that she unknowingly became queen after her father passed away on 6 February 1952.

But she was not informed until the following afternoon after she had returned to a fishing lodge called Sagana, 20 miles away, that she had been given as a wedding present.

The couple had flown from Heathrow to Kenya on 31 January and were seen off by the king himself, who waved goodbye to them as he stood in the bitter cold.

Upon arriving in Kenya, they travelled up-country to Sagana before driving to Treetops after lunch on 5 February.

Pubs could stay open into the early hours to celebrate the Queen's Platinum Jubilee

Due to their remote location, at the now-famous game-viewing lodge, the news of the king's death took a while to reach the royal party.

Royal historian Dr Ed Owens notes that the official announcement of the king's death came from Sandringham on the morning of 6 February 1952.

The BBC then broadcast the news that the king had died in his sleep and had been found that morning by a servant.

It came first to a senior courtier, who passed it to the princess's private secretary, Martin Charteris, who then telephoned Prince Philip's aide.

Prince Philip broke the news to her beside a trout stream in the foothills of Mount Kenya at around 2.45pm on 6 February and informed her she was now Queen and head of the Commonwealth.

"Elizabeth did not receive the news immediately," Dr Owens confirms.

"Instead, her private secretary was asked by a local newspaper editor whether or not reports of the king's death were true. The private secretary then contacted Philip who told his wife that she was now queen."

'Acceptance of her destiny'

Elizabeth is said to have reacted to the news with the same sense of duty she has become synonymous with, putting aside her grief to write letters apologising for cancelling the rest of the tour.

Arrangements were then made for her to immediately fly home.

Royal commentator Richard Fitzwilliams said the Queen's response to the news "was an acceptance of her destiny, as shown by the fact that she instantly knew what she would be called, replying when asked, 'My own name, of course - what else'."

He added: "She is a deeply religious person and daunting though becoming Queen at 25 might be, she had already pledged to serve her whole life when she was 21.

"She must have grieved deeply for her father to whom she was devoted, but to the world, she appeared composed."

Mr Fitzwilliams said it is known that Prince Philip was "totally crushed by the news" of his father-in-law's death.

King's death 'shocked' nation

Elizabeth had been carrying out more and more of her father's engagements towards the end of his life, such as greeting foreign dignitaries and riding in his place for the Trooping the Colour.

After the king's death was announced on cold a wet day in February, his body was brought back to London from Sandringham to lay in state for three days in Westminster Hall.

George VI was then buried in St George's Chapel in Windsor on 15 February, with some 300,000 people filing by to pay their respects.

His funeral procession was also televised, which prompted the first significant wave of television sales, though the funeral service was broadcast by sound only.

Mr Fitzwilliams said the seriousness of the king's condition "had been concealed by his doctors and the news stunned Britain".

"It was, as Churchill said 'the worst'. It was also totally unexpected, as it was believed he was improving and he had been shooting the day before," he added.

Excitement about a 'fairytale' queen

Dr Owens said that the British public was "shocked and saddened by the king's passing".

"He was only 56 so the news came as a surprise," he said, but added that there was also "quite a lot of excitement about the accession to the throne of the young 'fairytale' queen".

"Whereas George VI's reign had been overshadowed by the abdication, war and austerity, Elizabeth II's reign seemed to promise that better times for the monarchy and country lay ahead," he said.

The Queen's Coronation took place a year later, on 2 June 1953, in line with tradition to allow an appropriate length of time to pass after a monarch dies before holding such festivals.

But Mr Fitzwilliams points out that rumour has it, as well as The Crown series, that Winston Churchill postponed the coronation as he wanted to "hang on as prime minister".

Nevertheless, it was the first such event to be televised, an idea of Prince Philip's, and witnessed by the people.