The Queen will no longer attend the Epsom Derby on Saturday, Buckingham Palace has announced.
She will instead watch the showpiece horse racing event – which is part of her Platinum Jubilee celebrations – on TV at Windsor Castle, the Palace said in a statement.
It's the second time in two days she has been forced to withdraw her attendance from Jubilee events because of ongoing mobility issues.
Until the pandemic, the Queen had only missed Derby Day twice in her reign. The Princess Royal is expected to officially represent her mother, the Queen, whose unprecedented 70 years on the throne will be celebrated by 40 jockeys who have ridden for the monarch, before they form a guard of honour at Saturday's Derby.
At a reception at London's Guildhall on Friday, Kate Middleton, the Duchess of Cambridge, is said to have told an attendee the Queen is "fine" but had found the day "very tiring", The Sun reports.
Gill Smallwood, from Bolton, spoke with Kate and asked how the Queen was doing.
Ms Smallwood said: "She (Kate) said 'yes, she was fine, it was just very tiring yesterday, and she (the Queen) had had a lovely, lovely time'."
On Friday, the Queen was set to join the National Service of thanksgiving at St Paul's Cathedral in central London. She would have been part of a large contingent including Prince Harry and Meghan Markle who have jetted in from the US.
The Queen's love of horse racing was referenced at the packed thanksgiving service at St Paul's Cathedral.
Archbishop of York Stephen Cottrell praised her for "staying the course" and said she was "still in the saddle", even though she was not able to attend.
The Queen has a deep faith and missing the religious service would have not been an easy decision.
Nonetheless, Buckingham Palace said she would not be in attendance at St Paul's.
"The Queen greatly enjoyed today's birthday parade and fly-past but did experience some discomfort," a statement issued on Thursday said.
"Taking into account the journey and activity required to participate in tomorrow's National Service of thanksgiving, Her Majesty with great reluctance has concluded that she will not attend.
💡The Queen leads the lighting of the Principal Beacon at Windsor Castle.
The spectacular @QGCanopy Tree of Trees outside Buckingham Palace will form the Principal Beacon throughout the weekend’s celebrations. pic.twitter.com/JFnGkoja5o
On Thursday, the Queen appeared from Buckingham Palace with a walking stick to begin four days of public events to mark her historic Platinum Jubilee. The Jubilee marks 70 years of the Queen's reign.
The 96-year-old was seen using a walking stick as she made her way onto the balcony with her cousin, Prince Edward, Duke of Kent, 86. She was later joined by the extended family but there were some big names left out of the photo op including princes Harry and Andrew.
Though her appearance at the event had been in doubt after facing mobility problems, the aid of a walking stick and a bill of good health over the last few weeks allowed the monarch to take a salute from mounted troops from the balcony of Buckingham Palace, under the fluttering royal standard.
The scandal-plagued prince had already been sidelined from most events.
Buckingham Palace confirmed the Duke of York's positive result on Thursday.
"After undertaking a routine test the Duke has tested positive for Covid and with regret will no longer be attending tomorrow's service," a Palace spokesman said.
Andrew was last seen horse riding, seemingly in fine health, on Wednesday close to Windsor Castle, according to Sky News UK.
It's also understood that he saw the Queen in recent days. That could be a worry considering the full weekend of activities the Queen has planned and her frail health.
The BBC said Andrew had undergone regular testing and had not seen the Queen since he tested positive.