Image source, PA Media
The Queen will attend the Remembrance Sunday service at the Cenotaph after taking time away from her duties for her health.
The 95-year-old monarch has been under doctors' orders to rest for three weeks after spending a night in hospital.
The event will see the return of pre-pandemic numbers of veterans, military and onlookers.
The prime minister will join members of the royal family in laying a wreath at the war memorial in central London.
The National Service of Remembrance in Whitehall, which commemorates the war dead, will return to normal this year after the coronavirus pandemic saw the event closed to the public last year, with limited numbers of veterans and military personnel taking part.
Hundreds of servicemen and women will line up around the Cenotaph, and nearly 10,000 veterans will march past the war memorial, with large crowds expected to watch.
A national two-minute silence will be held at 11:00 GMT am on Sunday to remember those who fought and died in past conflicts, with ceremonies taking place at war memorials across the country after being scaled back last year.
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Buckingham Palace has said it was the Queen's "firm intention" to attend the wreath-laying service after she missed several other events, including the Festival of Remembrance at the Royal Albert Hall on Saturday, after being ordered to rest by royal doctors.
She spent a night in hospital on 20 October undergoing preliminary tests.
The monarch, who lived through World War Two as a teenager, is head of the armed forces and attaches great importance to the service.
Image source, PA MediaImage caption, The Queen is expected to watch the service from the balcony of a government building, as she has in previous years including 2019 (pictured here)
The Prince of Wales will lay a wreath at the top step of the Cenotaph on the Queen's behalf while she watches on from the balcony of a government building, as in previous years.
Prince Charles, who celebrates his 73rd birthday on Sunday, has placed the wreath on behalf of his mother since 2017.
Senior politicians will also wreaths, including Boris Johnson and Labour leader Sir Keir Starmer.
Mr Johnson said it was a moment to "come together to remember those who sacrificed everything in service of our country".
Image source, PA MediaImage caption, Last year saw a scaled-back service due to the coronavirus pandemic
Sir Keir said it was "a time for us all to step, reflect and remember those millions of people from Britain and the Commonwealth who have kept us safe through their service and sacrifice".
Another to lay a wreath will be Chief of the Defence Staff General Sir Nick Carter, who said it was an "honour" to do so on behalf of "all those who have lost their lives in the service of our country".
He said: "They died to protect the free and open way of life that we enjoy today."
Armed forces charity the Royal British Legion (RBL), which holds its Poppy Appeal in the run up to Remembrance Sunday each year, said this year's march would include hundreds of young people from the Cadets, Guides and Scouts.
RBL assistant director Bob Gamble said it was "vital the torch of Remembrance is passed to younger generations".
Also marching will be 21 LGBT+ veterans, including the first transgender officer to serve openly in the British Armed Forces.
Caroline Paige, who served in the Royal Air Force for 35 years as a navigator on fast jets and battlefield helicopters, said it would be a proud and emotional moment.
"It will be fantastic to see all the veterans together marching for the first time, bearing in mind that many of them were dismissed from the service, and it's just so nice to see them as part of the military family," she said.
Remembrance Sunday: The Cenotaph will be on BBC One from 10:15 GMT on Sunday.
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