Queen Elizabeth II, the UK's longest-serving monarch, has died at Balmoral aged 96, after reigning for 70 years.
With her death, her eldest son Charles, the former Prince of Wales, will lead the country in mourning as the new King and head of state for 14 Commonwealth realms.
In a statement, Buckingham Palace said: "The Queen died peacefully at Balmoral this afternoon.
"The King and the Queen Consort will remain at Balmoral this evening and will return to London tomorrow."
Former New Zealand television journalist Simon Walker, who was communications secretary to the Queen for three years, told Morning Report weeks of sadness can be expected across the UK and Commonwealth.
"Liz Truss the new Prime Minister just described the Queen as the rock on which modern Britain was built, and I think there's quite a lot of truth in that.
"If you think back to 1952 when she became Queen, so much has happened over that period, in this country and of course, so much in the Commonwealth and around the world, and she's been the one point of continuity throughout that period.
"Britain's had 15 Prime Ministers, the United States has had 16 presidents over that period, and the one kind of constant figure has been the Queen."
