The Queen has pulled out of an appearance at the State Opening of Parliament tomorrow.
A spokesman for the palace says Her Majesty has opted to miss the annual event - which ushers in the new political year - because she continues to have issues with her mobility.
The "reluctant" decision was made today in consultation with her doctors, the Buckingham Palace representative added.
Instead, Prince Charles will read The Queen's speech on her behalf.
The Queen's throne will remain empty in the House of Lords, and the Prince of Wales and the Duchess of Cornwall, who is also attending, will sit in their usual seats.
Prince William will also be in attendance for his debut State Opening appearance. The Imperial State Crown will still travel to Parliament.
Palace aides say Her Majesty has a busy diary this week with a call with Australia undertaken today, a planned Privy Council and PM audience, virtual and by phone, on Wednesday.
The Queen is expected to undertake some private engagements later in the week
The Letters Patent authorised by Her Majesty delegate to Counsellors of State the Royal function of opening a new session of Parliament. In this instance, it enables The Prince of Wales and The Duke of Cambridge to jointly exercise that function.
No other functions have been delegated by Her Majesty.
The Buckingham Palace spokesperson said: "The Queen continues to experience episodic mobility problems, and in consultation with her doctors has reluctantly decided that she will not attend the State Opening of Parliament tomorrow.
"At Her Majesty’s request, and with the agreement of the relevant authorities, The Prince of Wales will read The Queen’s speech on Her Majesty’s behalf, with The Duke of Cambridge also in attendance."
A royal source says: “The decision was taken today.”The Queen has also announced she will miss the royal garden party season due to start this week.
Every summer, up to three garden parties take place at the Palace and at the Palace of Holyroodhouse in Edinburgh - although they have not been held for the past two years due to the pandemic.
Last week it was revealed that the parties would be returning this summer, but the 96-year-old Queen would not be attending any.
Instead other members of the royal family will take her place at the events.
A spokesman said: “Her Majesty the Queen will be represented by other members of the royal family at this year’s garden parties, with details on attendance to be confirmed in due course.”
The parties are due to take place at Buckingham Palace on May 11, May 18 and May 25. The one at the Palace of Holyroodhouse will take place on June 25.
They will celebrate the Queen's Platinum Jubilee and those invited are guests who have been deemed to have made a positive contribution to their communities.
The head of state, who has mobility issues, has missed a number of major events this year but has been carrying out virtual engagements and her other duties.
Her mobility issues may even lead to last-minute cancellations for her Jubilee celebrations - which are just weeks away.
It has emerged that Her Majesty is likely to decide on the day whether she will make appearances at each of the events.
Over the course of the Jubilee weekend, she is expected to appear at Trooping the Colour on the Thursday, a church service at St Pauls's Cathedral on the Friday and at the Epsom Derby on the Friday.
However, decisions on her appearances across the weekend are not likely to be confirmed until the day.
A Palace spokesman said: “The Queen is looking forward to the weekend and will be taking part in the celebrations but her presence will not be confirmed until much nearer the time or even on the day itself.”
With less than a month to go, the Palace has released further details, including how Jubilee arrangements have been tailored for the Queen’s comfort.
The Queen is expected to travel by car to the national service of thanksgiving celebrating the Platinum Jubilee and dispense with ceremonial elements like a coach to ensure her comfort.
The changes mirror arrangements made for the monarch, who has mobility issues and sometimes walks with the aid of a stick, for events at Westminster Abbey where she has arrived via a door that shortens the distance to her seat.
And Her Majesty has even limited other royals from appearing at one Jubilee event.
She has banned Prince Harry, Meghan Markle and Prince Andrew from appearing on the Buckingham Palace balcony after the Jubilee's momentous Trooping the Colour.
It has been revealed that she is limiting the balcony appearance after the special Platinum Jubilee event to working royals only.
The monarch’s decision to only include royals carrying out official public duties was taken “after careful consideration”, Buckingham Palace said.
However, despite the seeming snub, Harry and Meghan have confirmed that they will come to the UK to attend the Jubilee celebrations this summer and will also bring their children Archie and Lilibet - who has yet to meet her great grandmother the Queen.
