Queen Elizabeth II embarks on her final journey

Queen Elizabeth II's coffin on Sunday left the Scottish retreat where she died as the late monarch embarked on her final journey with thousands of her mourning subjects expected to line the route.

A hush fell over the gathered crowd as the cortege carrying the queen's casket exited the gates of Balmoral Castle for Edinburgh at the start of an odyssey of mourning in the United Kingdom, culminating in her state funeral in London on September 19.

Six groundskeepers had loaded the oak coffin -- draped with a Scottish Royal Standard and a floral wreath -- into the black hearse that was to wind its way slowly on a six-hour journey to Scotland's capital.

Security escort vehicles and a mauve Bentley carrying the queen's only daughter Princess Anne made up the cortege passing through a series of towns before reaching Edinburgh, where it will rest for two days so people can pay tribute.

The first glimpse of her coffin for a grieving nation came a day after her son Charles III was formally proclaimed king, and after her warring grandsons William and Harry, and their wives Kate and Meghan, briefly reunited for a walkabout.

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The king himself will travel to Edinburgh on Monday for a prayer service, before the body of the queen, who died at Balmoral on Thursday aged 96, is flown to London on Tuesday.

Britain's longest-serving monarch will then lie in state for four days which is expected to draw at least a million people, ahead of a funeral set to be watched worldwide and attended by numerous heads of state.

"It's the end of an era, it's quite a big moment for the country and the world," said Nia Gray-Wannell, a scientist, who brought her two children to Balmoral to pay their respects.

"It felt like it would be worth coming."

While Charles' accession has pushed Britain into what newspapers have called the new "Carolean" era, Britain and the royal family are still coming to terms with the end of the Elizabethan age.

Prince William broke his silence with an emotional tribute to his beloved "Grannie" on Saturday.

"She was by my side at my happiest moments. And she was by my side during the saddest days of my life," said William, who has now become the Prince of Wales.

But the queen's death also brought a surprise show of unity from William, 40, and his younger brother Harry, 37, when they emerged with their wives to speak to well-wishers outside Windsor Castle, near London.

The sight of the two couples who have barely seen each other since 2020, together -- even if they separated to speak and shake hands with different sides of the cheering crowds -- will likely spark rumours of a reconciliation.

Pictures of the four were splashed on the covers of Sunday's newspapers.

"Reunited for granny," read the Sunday Mirror's headline, while the Telegraph ran with "Reunited in sorrow" and the Sun with "All 4 One".

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The Sunday Times focussed on the apparent frostiness, with the headline: "Warring Windsors' awkward truce to honour the Queen".

Senior royals including the queen's children, Princess Anne and Princes Andrew and Edward and their families also inspected flowers outside Balmoral, where the queen's body lay in the ballroom.

The symbolism of the queen's last journey will be heavy for Scotland -- a nation with deep royal links, but where there is also a strong independence movement intent on severing the centuries-old union with the United Kingdom.

Dedicated viewing points are being set up along the route, although mourners will be asked not to throw flowers at the convoy as it passes.

"We anticipate many, many people will be keen to pay their respects," First Minister Nicola Sturgeon said.

The queen's coffin will be taken to the Holyroodhouse Palace, the monarch's official residence in Scotland, where it will rest for a day.

King Charles and other royals will on Monday take part in a procession to convey her coffin along Edinburgh's Royal Mile to St Giles' Cathedral.

The following day the coffin will be flown by Royal Air Force jet to Northolt airfield near London, and driven to Buckingham Palace. Then, on Wednesday, it will be moved to Westminster Hall to lie in state.

King Charles will also visit Northern Ireland and Wales in a show of national unity, accompanied by British Prime Minister Liz Truss, who was only appointed by the late queen on Tuesday.

He has seen his popularity recover since the death of his former wife Diana, Princess of Wales, in a 1997 car crash, but he 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.

Charles vowed at the formal Accession Council at St James's Palace on Saturday that he would "strive to follow the inspiring example I have been set" by his mother during her "lifetime of service".

The centuries-old tradition was televised live for the first time, featuring a fanfare of trumpets and a court official wearing a feathered hat to declare him king from a palace balcony.

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Thousands of people have gathered outside Buckingham Palace and other royal residences in recent days to lay flowers and messages of condolence, or simply to experience history in the making.

But officials expect far more people to pay their respects while the queen lies in state, 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 attended by national leaders including US President Joe Biden, Australian Prime Minister Anthony Albanese and possibly Japanese Emperor Naruhito.

Her record 70 years on the throne were a constant during a turbulent time for Britain, from a world of post-war deprivation and the loss of its empire, to more recent traumas like the coronavirus pandemic.

Charles's coronation, an elaborate ritual steeped in tradition and history, will take place in the same historic surroundings of Westminster Abbey, as it has for centuries, on a date to be fixed.