King Charles III was officially announced as Britain’s monarch Saturday, in a ceremony broadcast live for the first time.

Charles automatically became king when his mother, Queen Elizabeth II, died on Thursday, but the accession ceremony is a key constitutional and ceremonial step in introducing the new monarch to the country.

The ceremony at St. James’s Palace, a royal residence in London, was attended by the Accession Council, made up of senior politicians and officials who advise the monarch. They met without Charles, officially confirming his title, King Charles III. The king then joined them to make a series of oaths and declarations.

“My Mother’s reign was unequalled in its duration, its dedication and its devotion. Even as we grieve, we give thanks for this most faithful life,” the king said in his personal declaration at the historic ceremony.

“I am deeply aware of this great inheritance and of the duties and heavy responsibilities of Sovereignty which have now passed to me.”

“In taking up these responsibilities, I shall strive to follow the inspiring example I have been set in upholding constitutional government and to seek the peace, harmony and prosperity of the peoples of these Islands and of the Commonwealth Realms and Territories throughout the world,” he added.

It’s the first time the ceremony has been held since 1952, when Queen Elizabeth II took the throne.

Charles, 73, was accompanied at the ceremony by his wife Camilla, the Queen Consort, and his eldest son Prince William. William is now heir to the throne and known by the title Charles long held, Prince of Wales.

Two days after the 96-year-old queen died at Balmoral Castle in Scotland following an unprecedented 70 years on the throne, people still came in their thousands to pay their respects outside Buckingham Palace in London. The scene was repeated at other royal residences across the UK and at British embassies around the world.

The monarch set the tone for his reign on Friday, vowing in a televised address to carry on the queen’s “lifelong service,” with his own modernizing stamp.

Britain has declared a period of mourning until the state funeral for Elizabeth. The date for that has not been announced but it is expected in a little over a week’s time.

King Charles III declared Saturday that the day of his mother’s funeral will be a public holiday.