As the new King settles into his role as monarch, he will need to rely on two women in particular to give him both emotional and professional support: the Queen and the Princess Royal.
While the Princess’s immense workload has often been overlooked in the past, her vast experience, as well as her close personal bond with her brother, will make her one of the most important figures of his reign.
The Princess, who is less than two years younger than the King, grew up with him, unlike their siblings Andrew and Edward, who are more than a decade younger. Their relationship is one of mutual respect as well as much laughter, and they have always loved spending time together.
One friend of the King said: “In the same way that the Queen had Princess Margaret to turn to for most of her life, the King has the Princess Royal.
“There is something quite steadying for him having her around, because they are close and they love to share a joke, but she also absolutely respects the role he inhabits.
“They always seem very happy to be in each other’s company.”
The death of Queen Elizabeth II means that hundreds of patronages have now returned to the new sovereign, all of which must be either absorbed by him, reallocated to other members of the Royal family or allowed to lapse.
While the King has expressed a desire to streamline the monarchy, his ability to do so will be dictated by the number of official engagements he wants the Royal family to carry out each year, and without Princess Anne there would be a sizeable hole in the royal diary.
Now aged 72, the Princess is the patron of more than 300 organisations and has built up a reputation as the hardest-working member of the Royal family.
She has carried out more than 20,000 engagements to date, and in 2021 the Princess carried out 387 official engagements, two more than her elder brother.
Both of them completed far more duties than the next-busiest member of the family, the Duke of Cornwall and Cambridge, with 235 official engagements.
In theory, at least, the King could decide to downgrade the Princess Royal status in order to focus on the direct line of succession, but Buckingham Palace confirmed on Friday that the title Princess Royal was conferred upon her for life.
The title of Princess Royal is traditionally reserved for the eldest daughter of the monarch.
Princess Anne is the seventh woman to be given the title of Princess Royal, which was first bestowed on Princess Mary, the daughter of King Charles I, in 1642.
A decision will have to be made over the title Duke of Edinburgh, which returned to the monarch upon the death of Prince Philip, and which is expected to be given to the Earl of Wessex.