The first formal ceremony of King Charles' reign will take place this evening in London.
The Accession Council will proclaim Charles as king at St James Palace.
The event, which will take place about 8pm AEST (11am London time) will be televised for the first time.
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During the proclamation ceremony, flags will be raised to full mast and royal gun salutes will be fired.
The event is attended by the Privy Council, a collection of dignitaries which typically includes past and present members of the House of Commons and House of Lords.
The Lord President of the Privy Council, Penny Mordaunt, will announce the death of the Queen.
The clerk of the council will then read the Accession Proclamation, which will include the king's chosen title, which has already been announced to be Charles III.
The proclamation is then signed by the Prime Minister, Queen Camilla, Prince William and the Archbishop of Canterbury Justin Welby.
While it is not formally part of the ceremony, the Privy Council will then chant: "The queen is dead. Long live the king!"
King Charles will then sign two oaths to preserve the Church of Scotland, a tradition dating back to 1707.
Flags will return to half-mast the following day.
The Privy Council dates back to the Dark Ages.
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