Tearful crowds outside Buckingham Palace sang a forlorn "God Save the Queen" as news broke of Elizabeth II's death on Thursday.
Hundreds braved torrential rain to stand at the palace gates after it was announced that doctors had placed the monarch under medical supervision at Balmoral, her Scottish estate.
A vivid rainbow temporarily lifted spirits, but the mood turned mournful as the seismic news was announced.
Some wept as the Union Jack flag on the queen's London residence was lowered, before a numbed silence fell over the crowd.
Another rainbow appeared as the flag was lowered at her Windsor Castle residence outside London.
"She's been the queen for as long as I've been alive, she's been the queen for as long as my parents have been alive," currency broker Charlie Wolstenholme told AFP.
"So she's really a very, very important part of the fabric. You know, it's going to be terrible."
Suzan Antonowicz compared it to losing a family member.
"She is the mother of our nation. She was heroic in so many situations. My respect for her is incredible, but my love is even bigger. We will grieve our loss for years," she said.
Choking back the tears, Joshua Ellis, 24, said he was in "shock".
"Every time people needed support she was there. She was also a link to my grandmother, who was a huge fan of her and passed away last year."
(AFP)
ALSO WATCH: Queen mourning period: what we can expect over the next 10 days