Britain's King Charles III and Queen Camilla attend the Accession Council at St James's Palace, where he is formally proclaimed Britain's new monarch, following the death of Queen Elizabeth II, in London, Britain Sept. 10. Reuters-Yonhap

Two days after the death of his mother elevated him to the throne, King Charles III was officially proclaimed Britain's monarch Saturday, in a pomp-filled ceremony steeped in ancient tradition and political symbolism _ and, for the first time, broadcast live.

Charles, who spent seven decades as heir apparent, automatically became king when his mother, Queen Elizabeth II, died on Thursday. But the accession ceremony was a key constitutional and ceremonial step in introducing the new monarch to the country, a relic of a time before mass communications.

Scores of senior politicians past and present, including Prime Minister Liz Truss and five of her predecessors, gathered in the ornate state apartments at St. James's Palace for the meeting of the Accession Council.

They met without Charles, officially confirming his title, King Charles III. The king then joined them, vowing to follow his mother's ''inspiring example'' as he took on the duties of monarch.

''I am deeply aware of this great inheritance and of the duties and heavy responsibilities of sovereignty which have now passed to me,'' he said.

Speaking of his personal grief, he said: ''I know how deeply you and the entire nation, and I think I may say the whole world, sympathize with me in this irreparable loss we have all suffered.''

The new king formally approved a series of orders _ including one declaring the day of his mother's funeral a public holiday. The date of the state funeral has not been announced, but it is expected to be around Sept 19.

This is the first time the accession ceremony has been held since 1952, when Queen Elizabeth II took the throne.

Charles 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.

The ceremony ended with a royal official publicly proclaiming King Charles III the monarch from a balcony at the palace. In centuries past, this would have been the first official confirmation the public had of their new sovereign.

David White, the Garter King of Arms, made the proclamation flanked by trumpeters in gold-trimmed robes before leading cheers _ ''hip, hip, hooray!'' _ for the new king.

Gun salutes rang out in Hyde Park, at the Tower of London and at military sites around the U.K. as he announced the news, and scarlet-robed soldiers in the palace courtyard doffed their bearskin hats in a royal salute.

The proclamation was read out in the medieval City of London and at other locations across the U.K.

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 U.K. and at British embassies around the world.

Britain is holding a period of mourning for the queen, with days of carefully choreographed ceremonies marking the death of the only monarch most people have ever known.

The Proclamation of Accession of King Charles III at the Royal Exchange in the City of London, Saturday, Sept. 10, after King Charles III was formally proclaimed monarch. AP-Yonhap