It is official, King Charles III has been proclaimed Britain's new monarch. 

As you would expect, it was an occasion steeped in tradition.

While the accession ceremony happened inside St James's Palace, the public made the most of their chance to take part in the tradition.

Let's take a look at the key moments. 

1. 'God save the King' 

"God Save the King" rang out as members of the Accession Council repeated the words announced by the Clerk of the Council inside St James's Palace.

Richard Tilbrook read aloud the text of the proclamation for the first time in front of 200 members of the privy council. 

"Prince Charles Philip Arthur George is now, by the death of our late Sovereign of happy memory, become our only lawful and rightful Liege Lord, Charles III, by the grace of God of the United Kingdom of Great Britain and Northern Ireland, and of his other realms and territories, King, head of the Commonwealth, Defender of the Faith," he said. 

"God save the King!"

This was the first part of the ceremony and happened without King Charles III in the room.

Former British prime ministers stood side by side, including Boris Johnson, Theresa May, and David Cameron as the proclamation was read. 

2. Charles makes a declaration for life

Charles has vowed to dedicate the remainder of his life to his duties as King. 

"I am deeply aware of this great inheritance and of the duties and heavy responsibilities of sovereignty which have now passed to me," King Charles III said.  

"In carrying out the heavy task that has been laid upon me on to which I now dedicate what remains to me of my life, I pray for the guidance and help of Almighty God."

William and Camilla stood by his side and signed the proclamation as witnesses.

It is the first time they have been seen together since the Queen's death. 

"In all this, I am profoundly encouraged by the constant support of my beloved wife," King Charles III said. 

All 200 members of the council present signed the proclamation as witnesses.

3. 'Three cheers for His Majesty the King!' 

The proclamation was then read out twice to the people of London. 

Firstly at St James's Palace and then at the Royal Exchange.

Members of the royal guard removed their bearskin hats at St James's Palace and gave three cheers to the King before the national anthem played.  

Crowds of people lined the street with their phones up capturing the moment as the procession made its way to the Royal Exchange.  

The crowd remained silent as the proclamation was read a third time.

They then gave three cheers to the King and sang the national anthem.