Sunday marks the final full day of the Queen’s lying in state.
Thousands of people are still joining the queue to pay their respects, as heads of state continue to arrive in London ahead of Monday’s funeral.
Irish president Michael D Higgins and Taoiseach Micheal Martin are expected to join those who have signed an official book of condolence at Lancaster House.
The King will hold an audience with Prime Minister Liz Truss at Buckingham Palace before he and the Queen Consort host overseas dignitaries there later, in what is described as an “official state event”.
A service of reflection for the Queen at the Kelpies sculptures near Falkirk, Scotland, will see 96 lanterns, one for each year of Her Majesty’s life, being lowered into the pool of reflection at the foot of the Queen Elizabeth II Canal, before wreaths are placed into the water.
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A pre-recorded tribute to the late monarch by the Queen Consort will be broadcast on the BBC shortly before 8pm.
After it, members of the public will be invited to observe a one-minute silence to remember the Queen.
The lying in state period will end at 6.30am on Monday, which will be a national bank holiday to allow as many people as possible to watch the Queen’s funeral, which will be shown on big screens across the UK, including at Hyde Park in London; Centenary Square in Birmingham; Coleraine Town Hall in County Londonderry, Northern Ireland and Holyrood Park in Edinburgh.
It will also be broadcast live at around 125 cinemas and several cathedrals throughout the UK.