As the eldest son of the Queen, Charles has now become King with Camilla, formally the Duchess of Cornwall, now known as the Queen Consort.
The Queen passed away "peacefully" at Balmoral, Aberdeenshire on Thursday (September 8) afternoon with Charles and Anne both said to have been by her side.
The Royal Family confirmed the news, writing on their official website: "The Queen died peacefully at Balmoral this afternoon. The King and The Queen Consort will remain at Balmoral this evening and will return to London tomorrow."
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As the eldest son of the monarch, the former Prince of Wales received the title from the Queen in 1958 due to the heir to the throne traditionally holding the title despite Charles becoming heir in 1952.
However following the tragic news, many have been left wondering who the new Prince of Wales is. Here's what you need to know.
Who will become the Prince of Wales now Charles is King?
Prince William is expected to be the next Prince of Wales as the eldest son of Prince Charles however while this is the likely scenario, the decision comes down to what Charles, as King, decides to do and whether or not he will grant his son the title.
Despite not automatically being given the Prince of Wales title, he has been given another title with Prince William now set to become the Duke of Cornwall and the Duke of Rothesay in Scotland as his father ascends the throne.
This means that he and Kate are now officially known as the Duke and Duchess of Cornwall and Cambridge.
What is the Investiture of the Prince of Wales?
The investiture of the Prince of Wales is the ceremony formally acknowledging a new Prince of Wales. The Prince is presented and invested with the insignia of his rank and dignity, in the manner of a coronation. An investiture is purely ceremonial.
In the 1969 ceremony, the Queen gave Charles the symbols that marked him as Prince of Wales; the sword, coronet, ring, rod and mantle. In addition to the 4000 guests present in the castle, 19 million watched on TV in the UK at home and another 500 million watched around the world.
Where will William be invested?
In 1911, the future King Edward VIII was invested in Caernarfon Castle. The present Prince of Wales, Prince Charles, was also invested there in 1969.
There is no suggestion that Caernarfon would host William's ceremony. If chosen, however, the Prince does have connections to the area having lived and worked in Anglesey where he trained with the Royal Air Force while living with then girlfriend, Kate Middleton.
You can follow our rolling news blog on all the latest updates from her passing here.
