Queen Elizabeth will miss the Remembrance Sunday (14.11.21) service after spraining her back.
The 95-year-old monarch was previously said to have the "firm intention" of attending the service, after taking time away from her duties for health reasons, but Buckingham Palace has announced that she will not be able to attend.
Buckingham Palace said in a statement: "The Queen, having sprained her back, has decided this morning with great regret that she will not be able to attend today's Remembrance Sunday service at the Cenotaph.
"Her Majesty is disappointed that she will miss the service."
Members of the Royal Family, including Prince Charles and Duchess Camilla, the Duke and Duchess of Cambridge, the Earl and Countess of Wessex and Princess Anne will still attend as planned.
Prince Charles will lay a wreath at the service at the Cenotaph in London on behalf of Queen Elizabeth.
Sunday's service was set to be Queen Elizabeth's return to public duties, her first engagement since being advised to rest by doctors just over two weeks ago.
The commemorative event is one of the most significant dates in the Queen's calendar each year.
Buckingham Palace previously said: "As in previous years, Her Majesty will view the Service from the balcony of the Foreign, Commonwealth and Development Office building."