At the tender age of three, King Charles became heir to the throne when his mother became Queen following the death of George VI.
He's then spent 70 years preparing monarch, and when Her Majesty died at the age of 96 almost two weeks ago, he finally became monarch at the age of 73.
His mother's long reign means her experience and wisdom of being a monarch and head of state will have no doubt rubbed off on her son - and will help to shape his reign.
But there's also several things that Charles may want to do differently to his mother - and here we look at the ways Charles III's reign maybe different from Elizabeth II's?
Slimmed-down monarchy
One major change we could be set to see during Charles' reign is a much smaller, slimmed down monarchy with fewer key players.
The Firm has, of course, already undergone some major structural changes in the past few years.
Prince Harry and Meghan Markle have decided their future is not in the UK, while Prince Andrew is not expected to ever return to public life.
But the enforced alterations don't begin to scratch the surface of what's ahead, some believe as the King has reportedly been long prepping for the new era with Palace "hangers-on" firmly in his eye-line.
It is believed the core royal family will be made up of seven key players, who carry out royal duties - the King, Queen Consort Camilla, Prince William, Kate, Prince Edward, Sophie Wessex and Princess Anne.
Shake-up of royal residences
Not only is the number of working royals set to be slimmed down, it has also long been said that Charles may decided to shake up the distribution of royal residences.
It was reported earlier this year that Charles was considering opening the monarch's official residence of Buckingham Palace and gardens throughout the year, including when he is in staying there.
A source said that Charles is convinced that Buckingham Palace is symbolically the home of the monarch and that he should be based there when king.
However, it could be all change when it comes to the late Queen's beloved home of Windsor Castle, where she spent most of lockdown.
According to the Daily Mail's Richard Kay last year, the castle is being earmarked for Kate and William and Charles finds its location under the Heathrow flight path "too noisy".
Giving away Balmoral?
Throughout most of her reign, the Queen would retreat to her Balmoral estate each summer, where she would enjoy countryside walks with her dogs, riding her horses and picnics with her family.
But will King Charles, who has inherited Balmoral, keep up with this tradition? It remains to be seen as reports have suggested he wants to turn Balmoral into a museum dedicated to his late mother's memory.
A source speaking to the Mail On Sunday said: "Looking at the number of properties and the number of working members of the Royal Family, the King will be looking at the properties and asking: 'What value does this give to the public?'"
However, he may not be giving up on visiting the Scottish Highlands altogether - that's because the King has his own Birkhall estate, which he is known to love spending time at.
Christmas change?
One royal tradition that now hangs in the balance following the Queen's death is the traditional Royal Family Christmas at Sandringham.
The Queen would invite all of her family to her Norfolk estate for the big family get-together - and each Christmas morning, the royals would be spotted heading to church.
It's not clear if Charles will decide to keep up with this tradition - especially as he own another private country retreat in Gloucestershire called Highgrove.
Smaller coronation
When his mother the Queen was crowned, her coronation at Westminster Abbey was a grand and lavish affair.
But Britain in the grip of a spiralling cost of living crisis, the King is said to be acutely aware of the struggles facing ordinary people today.
And now His Majesty has vowed to have a slimmed down coronation to reflect that concern, a source revealed.
It “will be shorter, smaller and less expensive” than the Queen’s ceremony in 1953.
Although not expected to be crowned until next year, the 73-year-old will also use the event to launch his vision for a modern monarchy, while staying true to long held traditions of pageantry and pomp.
That includes inviting a congregation made up of Christian, Muslim, Jewish, Hindu and Buddhist faiths to his inauguration at Westminster Abbey.
A royal source said: "The King has long been an advocate of a streamlined or slimmed down monarchy and this project could certainly be said to fit with his vision.
"He has already spoken of his wish to continue his mother’s legacy and this includes continuing to recognise what the people are experiencing day by day.”
Travelling overseas
Although the Queen had travelled to all four corners of the globe throughout her 70-year reign, in recent years overseas visits stopped.
She last went abroad in 2015 to Malta and allowed her younger family members to represent her outside of the UK.
But now with Charles as King, it will mean the UK's monarch will be up for overseas visits once again.
And one report suggests that rather than visit one of the Commonwealth countries, it is looking increasingly likely he may instead head to Paris "as soon as next month" as part of a tour.
The visit would come as Britain tries to build bridges with France following Brexit.
More openness
Throughout the Queen's reign, she was a figure of mystique with few people really knowing her true thoughts on the issues of the day.
But when it comes to Charles, the public know far more about his character, personality, loves and passions.
And one friend told the Telegraph, this could mean he proves much more open than his late mother.
They said: "He has been much more open than the Queen because he comes from a generation that has been much more open. We will see his humanity and his humour, as we have always done.”
While a courtier added: "There is plenty of freedom for each monarch to do different things in their own way."
During his time as Prince of Wales, Charles was also vocal on several matters, including saving the planet and environmentalism.
And his biographer Penny Junor added: "My suspicion is that he won’t meddle in an obvious way, but he will quite legitimately talk to his Prime Minister in a more opinionated way than his mother."
