Princes William and Harry and their wives put on a rare united front Saturday to view tributes to Queen Elizabeth II, threatening to upstage their father Charles on the day he was officially proclaimed king.
The impromptu walkabout by William and Kate with Harry and Meghan, their first joint public appearance since March 2020, came as royal officials unveiled plans for the run-up to the queen's state funeral on September 19.
William, who has taken the title of Prince of Wales now his father is king Charles III, earlier broke his silence with an emotional tribute to his grandmother.
"I knew this day would come, but it will be some time before the reality of life without Grannie will truly feel real," said the 40-year-old, the eldest of Charles' two sons with the late princess Diana.
But it was his relationship with his brother Harry, who quit royal life in early 2020 and moved to the United States with his American wife, that looked set to dominate Sunday's headlines.
The two couples, once dubbed "the fab four", emerged from Windsor Castle together to inspect flowers and tributes left for the queen, who died on Thursday aged 96 after a record-breaking 70-year reign.
In his first speech as king on Friday, Charles had spoken of his love for his son Harry and daughter-in-law, in what was widely seen as an olive branch.
After a lifetime's apprenticeship, Charles was formally proclaimed king on Saturday in a ceremony filled with the kind of pomp the UK does so well.
A court official wearing a feathered bicorn hat declared the 73-year-old "our only lawful and rightful" monarch from the balcony of St James's Palace in London.
It followed an Accession Council meeting of senior royals, clergy and government, a centuries-old tradition seen live on television for the first time.
"I am deeply aware of this great inheritance and of the duties and heavy responsibilities of sovereignty, which have now passed to me," Charles said in a speech before swearing an oath.
"In taking up these responsibilities, I shall strive to follow the inspiring example I have been set."
Eight trumpeters accompanied the proclamation that was followed by a rousing three cheers for the new king by red-jacketed Coldstream Guards soldiers, doffing their distinctive bearskin hats.
Ceremonial gun salutes boomed simultaneously across the UK and the proclamation -- a relic from the past where the new monarch needed to be announced to their subjects -- was read publicly in Scotland, Northern Ireland and Wales.
William, the heir to the throne whose wife Kate takes Diana's old title of Princess of Wales, said he would honour the queen "by supporting my father, the king, in every way I can".
Charles automatically became monarch when the queen died, but the proclamation was the latest step in the set piece 10-day programme building up to her state funeral.
Since the queen died, crowds have massed and left flowers, cards and candles outside the royal residences from Buckingham Palace to Windsor and Balmoral, the Scottish estate where the queen died.
They have both mourned the queen and wished Charles well, with thousands more expected to line the streets in Scotland when the queen's coffin begins its journey to London on Sunday.
"I'm sad, but you have to move on. I think the king will be different," said 53-year-old Londoner Sarah Berdien.
"The queen has always been the queen -- always the same, no drama."
Recruitment worker Dany Van Laanen, 36, said Charles has "big shoes to fill" as he replaces his mother, who was the only monarch that most in the UK had ever known.
"I do hope he will manage to modernise the monarchy," he said.
Charles -- who has seen his popularity recover in recent years from the time of Diana's death in a 1997 car crash -- takes the throne at a moment of deep anxiety in Britain over the spiralling cost of living and international instability caused by the war in Ukraine.
The constitutional monarch, who is supposed to remain outside politics, has intimated he will now steer clear of pronouncements on issues that he has previously been outspoken on such as climate change.
British Prime Minister Liz Truss -- only appointed by the late monarch on Tuesday -- offered the nation's support to Charles in parliament on Friday as she acknowledged the "awesome responsibility" he bore.
The speaker of the House of Commons and selected senior MPs swore allegiance to the new king on Saturday and Charles met Truss again, plus the cabinet and the heads of the opposition parties.
The funeral on September 19 at Westminster Abbey is expected to be attended by heads of state and government, with US President Joe Biden among those who said they will come.
British security officials are planning what has been dubbed likely the "biggest policing and protective operation" in UK history.
The Kremlin said Russian President Vladimir Putin -- at loggerheads with the West over his invasion of Ukraine -- will not attend.
Senior royals including the queen's other children Princess Anne and Princes Andrew and Edward also greeted well-wishers outside Balmoral on Saturday.
Prince Andrew -- who has also stepped back from public duties over allegations, strongly denied, that he had sex with a teenage victim of convicted sex US offender Jeffrey Epstein -- thanked the public for their condolences.
On Sunday, the queen's coffin will be taken by road from Balmoral to Edinburgh, where it will rest in the Palace of Holyroodhouse.
The following day, Charles III will lead the cortege along Edinburgh's Royal Mile to the magnificent St Giles' Cathedral, where he and other royals will hold an evening vigil.
From the Scottish capital, the coffin will be flown to London on Tuesday to lie in state for four full days in Westminster Hall, the oldest building in parliament.
Officials expect more than one million people to attend to pay their respects, before the televised funeral service at Westminster Abbey opposite.
The funeral for the queen -- who came to the throne aged just 25 in 1952 -- will be a public holiday in the form of a Day of National Mourning.
Charles's coronation, an elaborate ritual steeped in tradition and history, will take place in the same historic surroundings, as it has for centuries, on a date to be fixed.