Charles will be formally proclaimed King at an accession council in an ancient ceremony at St James’s Palace on Saturday, which will be televised for the first time.
The accession council will be followed by the principal proclamation, the first public proclamation of the new sovereign, held at 11am. It is traditionally read by the Garter King of Arms in the open air to a trumpet fanfare from the Friary Court balcony at St James’s, with gun salutes fired in Hyde Park and at the Tower of London.
A second proclamation at the Royal Exchange in the City of London will be read one hour later, at noon. Separate proclamations will be read in Scotland, Wales and Northern Ireland at noon on Sunday.
During the ceremony, Charles will make a declaration and swear and sign an oath in the presence of privy counsellors, expected to include Camilla, the new Queen Consort, and William, now the Duke of Cornwall and Cambridge.
In recognition of the new sovereign, flags will be flown at full mast from the time of the first proclamation until after one hour after the proclamations in the other nations, before being lowered once more to half-mast.
Charles automatically became King on his mother’s death, and traditionally an accession council is convened within 24 hours of a sovereign’s death. But the late announcement of the Queen’s death meant there was insufficient time to organise it for Friday.
Historically, the entire privy council – the oldest legislative assembly still functioning in the UK and dating from Norman times – would be summoned to oversee the formal proclamation of a new sovereign.
However, with the number of privy counsellors standing at more than 700 – comprising mostly former and current politicians – restrictions have been put in place. About 200 will be summoned, with a ballot for the few remaining seats conducted.
The accession council must take place before parliament meets, and parliament should meet as soon as practicable after the death of a sovereign.
The King will be not present for the first part of the ceremony, which is presided over by the lord president of the council, who has ministerial responsibility for the privy council office.
Penny Mordaunt was appointed to that role by Liz Truss, though she has yet to be “declared” lord president at a privy council meeting because the event was postponed on Wednesday when the Queen was advised by doctors to rest.
The chosen privy counsellors first gather without the King to proclaim him sovereign, joined by great officers of state, the lord mayor and city civic party, realm high commissioners and some senior civil servants, and expected to include Camilla and William, who are already privy counsellors.
The death of the sovereign is announced, and the text of the accession proclamation is read aloud. This will include Charles’s title of King Charles III.
A platform party, comprising Camilla, William, the archbishop of Canterbury, the lord chancellor, the archbishop of York, the prime minister, the lord privy seal, the lord great chamberlain, the earl marshal and the lord president, then sign the proclamation.
It is only then that Charles enters to hold his first privy council. He will make a personal declaration about the death of the Queen, and then read and sign an oath to preserve the Church of Scotland, necessary because in Scotland there is a division of powers between church and state. Another oath, the accession declaration, to maintain the Protestant succession, is normally made several months later at the state opening of parliament.
Other business will be dealt with, including the use of the seals, to “facilitate the continuity of government”. Privy counsellors will sign the proclamation as they leave.
The official record of proceedings will be published in a special supplement to the London Gazette.
On Friday King Charles held his first audience with the prime minister, Liz Truss, and made his first televised address.
He pledged to to serve the country “with loyalty, respect and love” and paid tribute to the Queen, saying his mother’s was a “life well-lived”.
He also announced that his son William and William’s wife, Catherine, would now inherit the titles of Prince and Princess of Wales and said he wanted to “express my love for Harry and Meghan as they continue to build their lives overseas”.
