Photos: Charles III is proclaimed king in centuries-old ritual

King Charles III was officially proclaimed monarch on Saturday after the death of Queen Elizabeth II, in the first Accession Council ceremony to be held in 70 years.

The council, made up of 200 members - primarily current and former politicians and other dignitaries - proclaimed Charles III's ascension to the throne in the State Apartments of St. James's Palace in London.

The accession ceremony should pave the way for confirmation of the date of the funeral of Queen Elizabeth II, the UK's longest-serving monarch, which is expected to be held on Monday, Sept. 19 but has not been officially confirmed.

Charles III confirmed that the Queen's funeral will be a national holiday.

Saturday's ceremony, which dates back until at least 1837, was followed by the King's declaration and taking of an oath.

Charles III said he was "deeply aware" of the responsibility he has inherited from his mother. "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.

Former Conservative Prime Ministers Boris Johnson, Theresa May, David Cameron and John Major, along with former Labour PMs Gordon Brown and Tony Blair, were among attendees. Women, including May and Scottish First Minister Nicola Sturgeon, attended the ceremony for the first time.

Gun salutes rang out across the city, including from the Tower of London and Hyde Park, to mark the accession. Sixty-two rounds were fired near Tower Bridge.

Shouts of "Long live the King" were heard from thousands of spectators. Salutes were fired in several other UK locations, including Edinburgh Castle.

Parliament will meet later in the day so that members can take oaths of loyalty to the new sovereign.