"Following further evaluation this morning, The Queen's doctors are concerned for Her Majesty's health and have recommended she remain under medical supervision," Buckingham Palace said in a statement.
The 96-year-old monarch was scheduled to attend a virtual meeting of her Privy Council on Wednesday, a day after she appointed Liz Truss as the new UK Prime Minister. Truss is the 15th Prime Minister appointed by the Queen during her 70-year reign.
Appointing a new prime minister is one of the Queen’s core ceremonial responsibilities as Head of State – with others being the State Opening of Parliament and the signing of parliamentary bills into law.
In May, the Queen missed the State Opening of Parliament for the first time in 59 years. The palace cited the monarch’s “episodic mobility problems” but declined to divulge further details citing patient confidentiality.
Instead, Princes Charles and William took center stage at the event, with the heir to the throne reading the government’s legislative agenda for the year ahead on his mother’s behalf.
The ongoing mobility issues, which the Queen has faced for nearly a year since a brief hospital stay last October, have also hampered other occasions including her Platinum Jubilee celebrations in June.