The Queen is marking the 68th anniversary of her accession to the throne.
Gun salutes will be fired by the King’s Troop Royal Horse Artillery in Green Park and the Honourable Artillery Company at the Tower of London to commemorate the occasion.
The bells of Westminster Abbey, the gothic church where the Queen was married and crowned, will also ring out to mark Accession Day.
The monarch has faced a turbulent time in recent weeks, with the Duke and Duchess of Sussex preparing to quit royal life.
And the Queen’s second son, the Duke of York, is facing calls to speak to the FBI in the US.
Andrew, who turns 60 later this month, stepped down from royal duties in November after his disastrous Newsnight interview about his friendship with convicted sex offender Jeffrey Epstein.
The Queen – the nation’s longest reigning monarch – will mark the anniversary of her accession privately at Sandringham, where she has been staying during her winter break.
She was out and about on Wednesday – the day before her accession anniversary – opening Wolferton’s new pumping station, which dries out the surrounding marshland for farming on the Norfolk estate.
The Queen carried out the engagement 72 years after her father, King George VI, opened the original station in February 1948, and recalled how he used to walk his corgis there.
She also visited nearby RAF Marham on Monday to see training demonstrations of engine maintenance and weapons loading at the military base.
A fortnight ago, the Queen, 93, missed a planned meeting at her local Women’s Institute because of a slight cold.
The Duke of Edinburgh, 98, who spends much of his time on the Sandringham estate after retiring in 2017, spent four nights in hospital just before Christmas for treatment relating to a “pre-existing condition”.
The Queen is just two years away from celebrating her Platinum Jubilee – 70 years on the throne.
Elizabeth II has ruled for 24,837 days, passing her Silver, Golden, Diamond and Sapphire Jubilees.
Princess Elizabeth became Queen on February 6 1952, on the death of her beloved father.
She was just 25 and thousands of miles from home on a Commonwealth tour with Philip in Kenya when the King died in his sleep from lung cancer at Sandringham House.
The Queen usually returns to London soon after her anniversary.
She will be hosting a state visit by the Emperor of Japan at Windsor Castle in the spring.
Her granddaughter, Princess Beatrice, Andrew’s eldest daughter, is also preparing to marry property tycoon Edoardo Mapelli Mozzi later this year.