Prince William dashed back to the UK to stand in for his father when King Charles recently visited France with his wife, Queen Camilla.
The Prince of Wales was in the US to attend the second Earthshot Prize Innovation Summit, an event which coincided with both Climate Week NYC and the 78th session of the UN General Assembly, and where the finalists were unveiled.
In the absence of the king, the queen and Prince Harry, only Prince William, Prince Andrew and Princess Beatrice act on behalf of the monarch as Counsellors of State.
With controversies surrounding Prince Andrew and the deficit of trust between him and other royals, the King is left with only two options: Prince William and Beatrice.
It's believed that Prince William is acting solely on his father's behalf as Beatrice has her own family to look after.
In the absence of the monarch, two or more Counsellors of State are appointed by Letters Patent, to act in King Charles place.
The current Counsellors of State are Queen Camilla, Prince William, Prince Harry, Prince Andrew and his daughter Princess Beatrice.
There is a legal presumption that counsellors of state should act jointly and, as such, at least two are needed to act, with the absence of one possibly risking a legal challenge.