The Queen will not travel to Glasgow to speak at Cop26, Buckingham Palace has confirmed.
The Queen, who has been unwell and was hospitalised for tests, has "regretfully decided" not to make the journey in person, saying she is "disappointed" not to be able to attend.
She will instead deliver a speech to delegates via video message, due to be filmed at Windsor Castle later this week.
Following instructions from her doctors to rest and undertake only "light duties", the Queen has pulled out of a reception she was due to host on Monday.
A source emphasised the Queen's hopes that no other leaders will use her absence as an excuse not to attend the summit, very much wanting Cop26 to be a success.
Her video message will urge world leaders to take "meaningful actions" on climate change.
Buckingham Palace announced the change of plans in order to avoid the appearance of a last-minute health emergency for the Queen, who has taken the advice of medics. A source said she "remains in good spirits".
The Prince of Wales, Duchess of Cornwall and Duke and Duchess of Cambridge will all attend the Glasgow summit, continuing to represent the Queen as they press key players to make and keep their pledges on climate change and net zero emissions.
A spokesman said: "Following advice to rest, The Queen has been undertaking light duties at Windsor Castle. Her Majesty has regretfully decided that she will no longer travel to Glasgow to attend the Evening Reception of COP26 on Monday, 1st November.
"Her Majesty is disappointed not to attend the reception but will deliver an address to the assembled delegates via a recorded video message."
She is expected to hold a call with the Chancellor this evening ahead of the Budget.
Her Majesty returns to work
Earlier today, the Queen was undertaking "light duties" at Windsor Castle, on a video call for audiences with the ambassador from the Republic of Korea, Gunn Kim, and the ambassador from the Swiss Confederation, Markus Leitner.
It is the first time the 95-year-old head of state has been seen - albeit on a computer screen - since she hosted a busy evening reception for the global investment summit on October 19.
She cancelled a trip to Northern Ireland, was under strict orders to rest and faced preliminary tests in hospital on October 20 during her first overnight stay at a medical facility in eight years.
The Queen was wearing a yellow dress and her three-strand pearl necklace as she met Kim.
The Queen was also photographed at Windsor Castle in an image released on the royal family's social media accounts.
The monarch was shown side on, smiling as she sat in a chair with her hands in her lap, in front of her large computer screen. On the table were her folded glasses and several pages of typed briefing notes for the audiences.
She has been resting at home in Windsor Castle since Thursday morning when she returned from an overnight stay in hospital having undergone "preliminary tests".
On Wednesday, she spent the night in the King Edward VII hospital in London having undergone tests for unexplained symptoms.
On Sunday she missed a church service at Windsor's All Saints Chapel, and has not been seen walking her dogs since her hospital visit.
The Queen was said to be "knackered" due to a busy social life and her preference for late-night television, according to the Sunday Times.
She has kept up a busy schedule since returning from Balmoral at the beginning of October, with 19 engagements in 19 days.
She hosted a major Global Investment summit at Windsor Castle on Tuesday evening, where she looked bright and cheerful as she carried out her royal duties.
Her admission was not related to coronavirus.
Buckingham Palace has not commented on whether the Queen has received her booster Covid-19 jab but given her age it is likely she has had it.
The palace initially kept the Queen's stay in hospital a secret, saying on Wednesday she was resting at Windsor and in good spirits after pulling out of a Northern Ireland visit.
After news was leaked to the Sun, they confirmed she had been in for tests but had already returned home on Thursday and was in "good spirits".
The overnight stay was for "practical reasons", a source said.
It was the monarch's first overnight hospital stay in eight years. She spent a night at the private clinic in 2013 when she was treated for gastroenteritis.
Her doctors and aides have been awaiting the results of tests and input from specialists, before they could advise the Queen on when she can sensibly be back in action in public.