Prince Charles is to read the Queen’s Speech at the State Opening of Parliament for the first time in history.
The Queen will not attend the ceremony on Tuesday, Buckingham Palace confirmed, which sets out the government’s policies and proposed legislation for the new session.
The monarch “reluctantly” pulled out of the occasion as she continues to experience “episodic mobility problems” with royal doctors advising her against attending.
The announcement marks a significant move towards the handing over of sovereign duties to Prince Charles.
The 96-year-old monarch has missed the ceremony only twice during her 70 years on the throne.
The Palace said in a statement: “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.”
The first time she missed the event took place when she was pregnant with Prince Andrew in 1959 and just before Prince Edward’s birth in 1963. On those occasions the Lord Chancellor read the speech on her behalf.
Prior to the event, Buckingham Palace drew up contingency plans for Prince Charles to read the speech amid concerns Her Majesty would be unable to attend.
The palace had said she was aiming to deliver the speech but her attendance would only be confirmed on the day.
For the past two state openings the Queen opted to travel to the Palace of Westminster by car, rather than carriage.
In recent months the Queen has missed a number of engagements because of mobility problems, including the royal garden party season.
Prince Charles already takes the place of the Queen at the Cenotaph on Remembrance Sunday.
He has also supported her at the State Opening of Parliament since the retirement of the Duke of Edinburgh in 2017.
Many of the events involve standing for long periods which the Queen is no longer able to do.
It has raised questions about which events she will be able to attend as part of the Platinum Jubilee celebrations next month.