Britain's Queen Elizabeth II.
The Queen has pulled out of the state opening of parliament on Tuesday due to ongoing mobility troubles.
Her throne will remain empty while Prince Charles delivers the speech in her place, Buckingham Palace said.
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 episodic mobility issues are said to be a continuation of the problems the Queen has suffered since the autumn.
The 96-year-old monarch was hospitalised in October and has since been undertaking mostly virtual engagements.
She has missed events at Easter and it was recently announced she would not host royal garden parties this year.
On Sunday, the palace revealed that the Queen’s attendance of her platinum jubilee celebrations next month may not be confirmed until “the day itself”.
Tomorrow’s state opening will be the first the Queen has missed in nearly 60 years, having been absent in 1959 and 1963 due to pregnancies.
On those occasions the Queen’s speech was read out by the Lord Chancellor but on Tuesday Prince Charles will deliver it for the first time.
The speech is used by the government of the day to promote its legislative agenda for the year ahead.
This year the main themes are expected to be energy and the cost of living, dirty money, Channel 4 privatisation and changes to Northern Ireland’s post-Brexit border arrangements.