Britain's King Charles will address a country in mourning on Friday following the death of his mother Queen Elizabeth, the only monarch most Britons ever knew and the "spirit of the nation" for seven decades.
Charles, who raced to be by the side of the queen at her Scottish home on Thursday, was due to travel back to London with his wife Camilla, now Queen Consort, before meeting the prime minister and making a televised statement.
The death of the queen, Britain's longest-reigning monarch and a towering presence on the world stage for 70 years, has drawn condolences from around the world.
Waking up to their first day without a woman once described by her grandson Harry as "the nation's grandmother", members of the public began gathering again outside Buckingham Palace to lay flowers and take photos of the growing memorial there.
Billboards across the city displayed messages of condolence and newspapers ran front-page photo tributes to the queen.
Buckingham Palace said there would a period of mourning to be observed by members of the family and the royal household until a week after the funeral, the date of which has not yet been confirmed but is expected in about 10 days time.
An online book of condolence was also opened.
At the remote Balmoral Castle in Scotland where she died on Thursday and where her family are gathered, people also arrived to pay their respects.
"She was amazing. She was like everyone's granny. She always managed to capture the mood with her words," said Kay McClement, 55, who came with a friend to leave flowers at the castle.
People also gathered at Buckingham Palace, the queen's home in central London, to lay flowers outside the famous black railings.
"I brought my young daughter here, because even though she won't remember it, we can tell her she was here as history was happening," said railway worker Liam Fitzjohn, 27.
"She's all we ever knew, we will never have a queen like that again."
The government said in a statement it expected large crowds to gather at royal residences. "We expect significant crowding and delays on some public transport," it said.
Elizabeth was head of state of the United Kingdom and 14 other realms including Australia, Canada, Jamaica, New Zealand and Papua New Guinea.
Charles, who automatically succeeded her as king, said the death was a moment of great sadness for himself and his family.
"We mourn profoundly the passing of a cherished Sovereign and a much-loved mother. I know her loss will be deeply felt throughout the country, the Realms and the Commonwealth, and by countless people around the world," the 73-year-old said in a statement.
He is expected to meet Prime Minister Liz Truss on Friday before later addressing the country.
There will be gun salutes at London's Hyde Park and at the Tower of London and the bells at Westminster Abbey and St Paul's will toll. At Windsor Castle, the Sebastopol Bell, captured during the 19th Century Crimean War and which is only struck to mark the death of the sovereign, will toll.
Regular business in parliament was replaced with a special session, from 1100 GMT, for lawmakers to pay tribute to the queen. Parliament will also convene on Saturday, something it rarely does, and will approve a message of condolence to the king.
News that the queen's health was deteriorating emerged shortly after midday on Thursday when a palace statement said she had been put under medical supervision, prompting her family to rush to Scotland.
The queen had been suffering from what Buckingham Palace had called "episodic mobility problems" since the end of last year, forcing her to withdraw from nearly all her public engagements. Her husband of 73 years, Prince Philip, died in 2021.
Her last public duty came only on Tuesday, when she appointed Truss prime minister - the 15th of her reign.
"The death of Her Majesty the Queen is a huge shock to the nation and to the world," Truss said outside her Downing Street office where the flag, like those at royal palaces and government buildings across Britain, was lowered.
"Through thick and thin, Queen Elizabeth II provided us with the stability and the strength that we needed. She was the very spirit of Great Britain – and that spirit will endure."
Trade unions cancelled planned strikes and the BBC national broadcaster said that "as a mark of respect" it had called off its remaining 'Proms' concerts - whose patriotic, flag-waving finale was due to take place on Saturday.
Condolences poured in from leaders and people around the world.
"Her legacy will loom large in the pages of British history, and in the story of our world," US President Joe Biden said in a statement.
"We are all very affected because she was such an important figure. Not only in England but worldwide," said Madrid resident Alejandra Mas, while in Berlin, Christoph Krebs said: "I thought to myself, 'at 96 the woman is allowed to die'."
Queen Elizabeth II, who was also the world's oldest and longest-serving head of state, came to the throne following the death of her father King George VI on Feb. 6, 1952, when she was just 25.
She was crowned in June the following year. The first televised coronation was a foretaste of a new world in which the lives of the royals were to become increasingly scrutinised by the media.
Elizabeth became monarch at a time when Britain retained much of its old empire with Winston Churchill her prime minister, while Josef Stalin led the Soviet Union and the Korean War was raging.
Bereft of its symbol of continuity and resilience, Britain begins its new era in grave economic crisis, marked by ructions with Europe and a populace disaffected by years of political strife and scandal.