Charles praises Queen's reign as he is formally confirmed as king

PA Media King Charles IIIPA Media
King Charles III described the Queen's death as an "irreparable loss"

King Charles III has praised the Queen's "unequalled reign" after being proclaimed king at a ceremony at St James's Palace.

The King became the monarch after the death of his mother, but a meeting formally confirmed it on Saturday.

He also approved the day of the Queen's funeral, Monday, 19 September, being a bank holiday.

Speaking before the Accession Council, the King said his mother's death had been an "irreparable loss".

Meanwhile, senior MPs in the House of Commons, including Prime Minister Liz Truss, swore allegiance to the new monarch.

HM Queen Elizabeth II 640x55
HM Queen Elizabeth II black line

Making his address in the State Apartments of St James's Palace in London, King Charles said: "It is the greatest consolation to me to know of the sympathy expressed by so many to my sister and brothers and that such overwhelming affection and support should be extended to our whole family in our loss."

He later spoke of the Queen's "selfless service", saying: "My mother's reign was unequalled in its duration, its dedication and its devotion.

PA Media Details about the throne room at St James's Palace.PA Media
King Charles gave his speech in the Throne Room at St James's Palace.

"Even as we grieve, we give thanks for this most faithful life."

The King added he would "strive to follow the inspiring example" he was set by his mother in taking on the "heavy responsibilities of sovereignty".

It is the first time the historic ceremony, which dates back centuries, has been televised.

Watch: Charles III is proclaimed King, in a ceremony broadcast for the first time

The King himself was not present for the first part of the meeting when he was proclaimed monarch by the Accession Council, made up of senior politicians, judges, and officials.

Six former prime ministers were in attendance at the accession ceremony
Six former prime ministers were in attendance at the accession ceremony

Clerk of the Privy Council Richard Tilbrook proclaimed Charles "King, head of the Commonwealth, defender of the faith", before declaring "God Save the King".

The packed room, including all of the six living former British prime ministers, repeated the phrase. The proclamation was then read out on a balcony above Friary Court in St James's Palace.

2px presentational grey line
Analysis box by Sean Coughlan, royal correspondent

The new King paid warm tribute to his mother, but this was the point when Charles began to look forward to his own reign.

Before the Accession Council's ranks of senior politicians and public figures, King Charles dedicated the rest of his life to serving as monarch.

It was a mix of ritual, ornate language and constitutional practicality.

Charles is now the head of state and here was the seamless and symbolic transfer from one reign to the next, with oaths and signatures.

The inkpot used had been given to him by his sons, Prince William and Prince Harry.

The announcements also confirmed that the day of the Queen's state funeral would be a public holiday.

But here was the King publicly shouldering his new responsibilities, promising to follow in the Queen's example. It was the choreography of continuity.

2px presentational grey line
Reuters King Charles IIIReuters
The King greeted crowds as he arrived at Buckingham Palace from the ceremony

Just before the ceremony inside, hundreds of people were allowed through from the Mall, into the palace's outdoor Friary Court, to witness the proclamation up on the balcony.

They brought their babies and children and carried bunches of flowers. Some brought their dogs on a walk, diverted to witness the moment.

After the state trumpeters played a fanfare, the privy councillors who had left the ceremony and gathered outside raised their voices to say "God Save the King".

Cheers of "hip-hip hooray" were heard coming from people lining the roads both sides of the palace, and ceremonial guns fired close to nearby Green Park.

As senior figures from politics past and present filed away, senior Labour MP Harriet Harman described the ceremony inside as "solemn", both because of the death of the Queen and the weight of the occasion for the new King.

St James's Palace
The Accession Proclamation was made on a balcony at St James's Palace

The second reading of the Accession Proclamation was also met with applause and cheers outside the Royal Exchange in London on Saturday.

PA Media Members of the Royal Family read tributes left for the Queen.PA Media
Three of the Queen's children and their families read tributes to the Queen as they returned from a church service.

Taking her oath, the prime minister said: "I swear by almighty God that I will be faithful and bear true allegiance to His Majesty King Charles, his heirs and successors, according to law, so help me God."

On Saturday afternoon, three of the Queen's children and their families viewed flowers and tributes left outside Balmoral after attending a prayer service at Crathie Kirk, near to the castle.

On their return to Balmoral they stopped their cars by the gates as they thanked well-wishers for coming to read the messages left for the Queen.

Reuters Prince Andrew and Princesses Eugenie and Beatrice read tributes to the Queen.Reuters
The Duke of York comforted his daughter Princess Eugenie as they read tributes to the Queen
Reuters Princess Anne outside BalmoralReuters
Princess Anne was joined by her two younger brothers and their families as they looked at tributes outside Balmoral

Prince Andrew was seen putting his arm around his daughter, Princess Eugenie, as she wiped a tear from her eyes, while the Countess of Wessex held Lady Louise's hand.

After around 10 minutes the family returned to Balmoral Castle.