A military parade, street parties and a balcony appearance by the royal family will on Monday begin four days of UK celebrations to mark 80 years since the end of World War II.
King Charles III, Prime Minister Keir Starmer and thousands of spectators will watch NATO personnel from the US, France and Germany, along with Ukrainian troops, in a military procession that will begin with Winston Churchill's 1945 victory speech, voiced by actor Timothy Spall.
As European countries gear up to celebrate Victory in Europe (VE) Day on May 8, the war in Ukraine is a reminder "that peace is never to be taken for granted", Charles told the Italian parliament last month.
"Today, sadly, the echoes of those times, which we fervently hoped had been consigned to history, reverberate across our continent," the king said.
Monday's procession will culminate in a fly past featuring aerobatic team the Red Arrows and 23 current and historic military aircraft, which the 76-year-old monarch and other working royals will watch from the balcony of Buckingham Palace.
It was from the same balcony on May 8, 1945, that King George VI and Queen Elizabeth, alongside their daughters princesses Elizabeth and Margaret, and then prime minister Churchill greeted tens of thousands of Londoners celebrating what Churchill declared the "day of victory in Europe".
That night, the two princesses, then 19 and 14, were allowed to leave the palace and join the jubilant crowds incognito.
Some 40 years later, Elizabeth, by then queen, described the night as "one of the most memorable" of her life.
Poppies, pubs and parties
This year's commemorations will take on extra poignancy given the fading of the "Greatest Generation".
This will be the last major commemoration for which "anyone will still be alive who actually served in the Second World War," monarchy specialist Robert Hazell of University College London told AFP.
Buckingham Palace will on Monday host a reception to celebrate veterans and people of the WWII generation.
Their numbers are dwindling, leaving younger generations increasingly disconnected from the conflict that shook the continent from 1939 to 1945.
"It's important to remember some of the poor devils who didn't make it like I did," 99-year-old Royal Air Force Veteran Dennis Bishop told AFP.
The first act on a chilly Monday morning in London was the draping of two huge Union Jack flags on the Cenotaph war memorial that honours Britain's war dead.
The usually bustling central London streets were deserted, except for The Mall outside Buckingham Palace, where hundreds of people set up camp with chairs and rugs.
"It's so emotional to be here today. Eighty years of peace and peace of mind, I don't know if we understand what achievement it is. Where would we be without them?" said Patrick Beacon, 76, who arrived with his wife at around 7 am (0600 GMT) to get the "best view".
Debt of gratitude
Among other events, there will be a party on HMS Belfast, one of the few surviving British warships from WWII which is moored on the banks of the Thames.
And people are invited to take part in hundreds of other parties, picnics, installations and commemorations that will take place across the country through the week until VE Day on Thursday.
On Tuesday, Queen Camilla will visit an art installation of around 30,000 ceramic red poppies, symbols of remembrance for the war dead at the iconic Tower of London.
Celebrations will draw to a close on Thursday with a two-minute national silence, observed by the royals and at government buildings at noon.
King Charles, who has been undergoing treatment for cancer for over a year, and Queen Camilla will attend a service of thanksgiving at Westminster Abbey, followed by a concert at London's Horse Guards Parade.
The royal family is hoping "nothing will detract or distract" from the celebrations after Prince Harry, Charles' youngest son, gave a bombshell interview on Friday, according to UK media.
Pubs across the country have been allowed to stay open two hours later as part of the celebrations.
"We owe a debt of gratitude to those prepared to make the ultimate sacrifice for our country," Prime Minister Keir Starmer wrote on X late Sunday.