London (AFP) - Queen Elizabeth II's eight grandchildren mounted a vigil around her coffin Saturday as US President Joe Biden flew in ahead of the state funeral being planned for Britain's longest-serving monarch.
King Charles III's sons Prince William and his brother Prince Harry stood guard around the crowned casket in London's Westminster Hall as members of the public, who had waited several hours to file past the catafalque, paid their last respects.
Queen Elizabeth's grandchildren, aged from 44 to 14, stood silently with their eyes lowered.
Harry -- who did two tours with the British Army in Afghanistan -- wore the uniform of the Blues and Royals cavalry regiment in which he served.
The move appeared to be the latest olive branch offered by King Charles towards his youngest son after Harry and his wife Meghan, now living in California, accused the royal family of racism.
No longer a working royal, Harry, 38, was stripped of his higher-ranking honorary military titles.The vigil will be the only time he will be seen in military dress at royal ceremonial occasions.
William and Harry, Prince Andrew's daughters Princesses Beatrice and Eugenie, Princess Anne's children Peter Phillips and Zara Tindall, and Prince Edward's children Louise and James silently stood guard around their grandmother's casket.
Edward's wife Sophie looked grief-stricken as she watched their children, 18 and 14 respectively, take on the most arduous public duty they have ever faced.
The personal sorrow of the queen's family has been playing out in the glare of intense international attention.
Beatrice and Eugenie paid a heartfelt tribute to "our dearest Grannie" shortly before the vigil.
"We, like many, thought you'd be here forever," the sisters said in a statement."And we all miss you terribly.
"You were our matriarch, our guide, our loving hand on our backs leading us through this world...For now dear Grannie, all we want to say is thank you."
They added: "We're so happy you're back with Grandpa," -- her husband Prince Philip, who died last year aged 99.
Charles, William greet queue
The vigil came hours after King Charles and his heir William staged an unscheduled London walkabout to thank those queueing overnight to pay their last respects.
"It means an awful lot that you're all here," William's Twitter account said afterwards.
Queen Elizabeth's death on September 8 aged 96, after a record-breaking 70 years on the throne, has sparked an outpouring of emotion.
Tens of thousands of people are braving waits that have stretched to more than 25 hours to file past her flag-shrouded coffin.
The royal visit delighted mourners who had waited through a chilly night.
Cries of "God save the king" came from the riverside crowd as the royals thanked the well-wishers.
"I'm so happy.He was so calm and friendly, and he was so gentle," said Geraldine Potts-Ahmad, a secretary in her late 50s, as she struggled to contain her emotions after shaking hands with King Charles.
"He is going to make the best king.That gentleness and that tenderness -- I saw the queen in that."
Some 435 people in the queue have needed medical treatment, often for head injuries after fainting, the London Ambulance Service said.
But Alison Whitham, an ex-nurse from Ashby in the English Midlands, said her 14-hour wait was well worth it after paying her final respects.
"It was very moving, very dignified, blissfully quiet," the 54-year-old said.
"The fact that you could just concentrate, with nobody holding phones up, was so lovely."
At 10:30 pm (2130 GMT) Saturday, the queue was estimated to be at least 17 hours long.
The public have until 6:30 am (0530 GMT) on Monday to view the coffin before the queen is honoured with Britain's first state funeral in nearly six decades.
King Charles meets PMs
King Charles is now the head of state of 15 separate countries and later met five of his prime ministers who have flown in for the funeral.
He held audiences at Buckingham Palace with Canada's Justin Trudeau, Australia's Anthony Albanese, New Zealand's Jacinda Ardern and The Bahamas' Philip Davis.
He also met Jamaica's Andrew Holness, who said the late queen was a "profoundly beloved monarch".
"Queen Elizabeth’s passing ushers in a new era for both the people of the United Kingdom and for the rest of the world, who knew only one head of the state for 70 unbroken years," he said on Twitter.
"Her legacy is vast, and her mark on the world will be talked about long into the future."
Trudeau said Queen Elizabeth "served for her entire life, and bore the weight of her duties with impeccable grace", after signing the book of condolence.
Biden is expected to visit Westminster Hall on Sunday and sign the book, before attending a reception for visiting dignitaries being thrown by Charles.
Security build-up
Police are mounting Britain's biggest-ever security operation for Monday's funeral.
London's Metropolitan Police chief Mark Rowley said it was a "monumental policing operation, which will culminate in us deploying the greatest number of officers in the Met's history for a pre-planned event".
Mourners have already begun setting up camp in central London to get a glimpse of the funeral procession.
"I went to princess Diana's funeral when I was a teenager, I was right outside the abbey, and the atmosphere was incredible," said Magdalena Staples, 38, who was camping outside Westminster Hall with her two children, aged nine and 10.
"I wanted my children...to have the same experience.We're camping for three nights, we've got hot clothes, snacks, a mattress and toilets nearby," she added.
The funeral ceremony at Westminster Abbey -- expected to be watched by billions around the globe -- will see 142 sailors pulling the gun-carriage bearing her lead-lined coffin.
It will be attended by more than 2,000 guests, but leaders from countries at loggerheads with the UK such as Russia, Belarus and Afghanistan have not been invited.
