The Queen has postponed a Privy Council meeting after she spent Tuesday handling the transition of power from Boris Johnson to Liz Truss.
A Buckingham Palace spokesperson said: “This means that the Privy Council meeting that had been due to take place this evening will be rearranged.”
“After a full day yesterday, Her Majesty has this afternoon accepted doctors’ advice to rest.”
The monarch, 96, has ongoing mobility issues and had been due to hold the Privy Council meeting virtually on Wednesday.
During the proceedings, Ms Truss would have taken her oath as First Lord of the Treasury and new cabinet ministers would have been sworn into their roles, and also made privy counsellors if not already appointed as one in past.
Doctors did not advise a hospital stay and Queen remains at Balmoral Castle, where she appointed Ms Truss, the 15th prime minister of her reign.
Mr Johnson also met the Queen at her Scottish retreat to offer his resignation, three years after she appointed him prime minister.
Her Majesty’s health has been scrutinised over the past year, as she has had to pull out of key events due to “episodic mobility problems”.
In October 2021, she used a walking stick at a Westminster Abbey service – the first time she had done so at a major engagement.
A week later, after a busy autumn programme, she was ordered to rest by her doctors and advised to cancel a trip to Northern Ireland.
The Queen was secretly admitted to hospital for “preliminary investigations” and had her first overnight stay in hospital for eight years on 20 October 2021.
For more than three months she carried out only light duties, including virtual and face-to-face audiences in the confines of Windsor Castle.
She waved to crowds from the Buckingham Palace balcony on the first day of her Platinum Jubilee celebrations on 2 June, later appearing at Windsor Castle.
But the next day she pulled out of the Platinum Jubilee Service of Thanksgiving at St Paul’s Cathedral after experiencing “discomfort” during the previous day’s celebrations.
In March, it was reported that the Queen would not return to living at Buckingham Palace but continue permanent residence at Windsor Castle.
The Queen joined by members of the royal family on the Buckingham Palace balcony in 2019
