The Queen was just 25 when her father, George VI, died suddenly making her the new Queen.
The then-Princess Elizabeth was in Kenya with Prince Philip and a team of staff at the time, and her husband had the heartbreaking job of giving her the news.
Not only did the young princess have to come to terms with losing her dad, she also had to take in the fact that she was now the Monarch - something that would completely change every aspect of her life.
But moments after being given the life-changing news, the future Queen walked over to staff and apologised to them.
Recalling the heartbreaking day on February 6 1952, Elizabeth’s lady-in-waiting Pamela Mountbatten says her boss was "completely calm".
The royal couple and their staff were in Kenya at the time, but the unexpected tragedy meant the Princess had to return home immediately to take care of arrangements and start her role as monarch.
Writing in her memoirs Daughter of Empire, she says: "She remained completely calm and said simply: 'I am so sorry. This means we all have to go home.'"
The team set to work planning their hasty journey back to Britain on the royal BOAC Argonaut, which had to be delayed for several hours because of a storm.
Ever aware of her public duty, Elizabeth immediately discussed the practicalities of her return to England.
But she also asked for an hour alone in her room.
They travelled back to London on the royal BOAC Argonaut, stopping to refuel in Libya.
Her staff also realised her mourning outfit had already been sent on by plane to the next stop on her royal tour.
When the royal plane touched down in London, a black dress was brought on board for her to change into before she emerged to the full glare of the press and public.
The Queen arrived back in mourning garb to meet dignitaries including PM Winston Churchill.
Her coronation took place the following year and was the first ever to be televised.