MPs and peers are to gather at the UK's Parliament to pay tributes to the Queen in a session of condolence.
Both the House of Commons and House of Lords are due to sit at 12pm to allow members to pay their respects, with normal politics on hold for a period of mourning.
The tributes, led by Prime Minister Liz Truss, are due to last all the way through until 10pm on Friday.
There will also be a rare Saturday sitting, where senior MPs will take an oath of allegiance to the King from 2pm, with condolences continuing again until 10pm.
The latter session will end with a “formal humble address” to the King, “expressing the deep sympathy of the House” following his mother’s death at Balmoral on Thursday, the House of Commons said in a statement.
Every MP will have the option of taking an oath to the King when the House returns but are not obliged to.
Parliament’s tributes come after tributes flooded in from across the political spectrum as the world digested news of the Queen’s death at the age of 96.
Truss hailed the longest-serving monarch as the “rock on which modern Britain was built”, while Sir Keir Starmer, the leader of the Opposition, said she was “a symbol of the best of us”.
SNP Westminster leader Ian Blackford said: "My thoughts, prayers and deepest condolences are with the family of Her Majesty The Queen. People across Scotland, the UK and the world will be mourning the loss of Her Majesty.
"The Queen was a constant figurehead throughout our lives, and she showed an inspiring commitment to the values of leadership, duty and service throughout her long reign."
Boris Johnson was among the six living former prime ministers of the Queen’s reign to pay his respects, two days after he met her at Balmoral to resign from office.
He said the Queen spread “magic around her kingdom” for an “unrivalled” 70 years and had a “simple power to make us happy”.
Commons Speaker Sir Lindsay Hoyle will determine the timetable in the House for the following days, but it is expected to be significantly reduced until after the state funeral as Parliament adjourns.
This means new laws cannot be passed until Parliament returns, though it could be recalled for pressing matters.
Buckingham Palace said the Queen died “peacefully” at Balmoral.
Her eldest son has become King Charles III.
