Her reign is now the second-longest of any monarch.
But the Queen's Platinum Jubilee was a reminder that while Her Majesty has long reigned over us, the Commonwealth must prepare for a changing of the guard.
Secret plans for 10 days following her death were shown to Australian Prime Minister Anthony Albanese after his election victory, and they are believed to have been updated in recent weeks.
The new plans include a national day of commemoration, which is likely to be a public holiday, The Australian reported.
Her funeral at Westminster Abbey will take place 10 days after her death, so any public holiday in Australia and New Zealand would likely take place within that period.
The Executive Council will later proclaim Charles King of Australia and New Zealand. This is likely to happen the day after the Queen dies, to synchronise with the Ascension Council's proclamation in the UK.
The proclamation is an official signing off of Charles acceding to the throne, but he will already be King - taking over from the moment the Queen passes.
Camilla, the Duchess of Cornwall, is also expected to be proclaimed Queen in a move that is likely to prove controversial.
Two RAAF planes will travel across the Pacific collecting leaders ahead of the funeral in London, The Australian reported.
Previous reports suggested that European heads of state would be put up at the Palace, while others would stay at Claridge's hotel.
The first sign that the Queen has died will be Her Majesty's private secretary calling the British Prime Minister - currently Boris Johnson - and uttering the phrase "London Bridge is down".
The news will then be passed on a strictly need-to-know basis to senior members of the British Cabinet and Commonwealth leaders.
As the news is broadcast around the world, a Buckingham Palace footman will pin a notice to the palace gates informing the public of the tragic news.
Large swathes of the world will then be plunged into 10 days of mourning.
The new King Charles will then tour the UK, heading to Wales, Scotland and Northern Ireland to attend services of remembrance.
The Queen's coffin will be transported from her home at Windsor Castle to Buckingham Palace, where it will remain for four days when it will be taken to Westminster Hall to lie in state for a further four days.
Charles will lead mourners in paying their respects, with hundreds of thousands of members of the public expected to be permitted to walk past Her Majesty's coffin.
The new king's Coronation is not expected to take place until around a year after the Queen's death, as was the case with her own Coronation following the death of King George VI.