Thousands of mourners have travelled to Buckingham Palace to pay tribute to the Queen, with some who waited for hours greeted by the new King.
After news of the Queen's declining health broke on Thursday afternoon, crowds began to gather outside the palace.
Twenty-four hours later, the gates were covered in several rows of flowers, candles, and presents.
As dawn broke in central London, there was a trickle of mourners, many of them commuters, stopping for a moment of reflection.
By lunchtime the trickle had become a torrent, with tens of thousands shuffling patiently up the length of Constitution Hill and beyond as they waited, umbrellas to shield them from the rain, to pay their respects.
Just after 2pm, King Charles and his Queen Consort, Camilla, arrived at the palace after travelling from Balmoral.
Getting out of their car, the royal couple greeted almost everyone in the front row outside the palace, shaking hands, accepting people's condolences, and even receiving a kiss on the cheek from one woman.
Flowers laid at the palace gates will be moved to a special floral tribute garden at Green Park, a royal spokesman said.
Mourners are also being encouraged to leave bouquets in Hyde Park.
Several hundred at Balmoral and Windsor
Meanwhile, slightly smaller crowds gathered at Windsor Castle, Balmoral, and Sandringham.
Sky News Scotland correspondent James Matthews said there were "several hundred" mourners at the main gate to the royal residence in Aberdeenshire.
"They had travelled from near and far, many to lay tributes in flowers at the gates of the royal estate," he said.
"'Thank you Your Majesty, our gracious lady,' was written on one card. 'Many thanks for your love and devotion to our country,' read another."
All the royal residences and estates will be closed until after the funeral.
Tonight at 8pm on Sky News: Watch the documentary Elizabeth II: A life of duty with Mark Austin, a look back at the extraordinary life of Britain's longest reigning monarch