Queen Elizabeth II has postponed a meeting of her Privy Council advisory group after doctors advised her to rest, Buckingham Palace said on Wednesday, a day after she named Liz Truss as Britain’s new prime minister.

“After a busy day yesterday, Her Majesty accepted the doctors’ advice this afternoon to rest,” the palace said in a statement.

“This means that the Privy Council meeting scheduled to take place tonight will be rearranged.”

The 96-year-old monarch, who is currently at her traditional summer retreat in Balmoral in the Scottish Highlands, has been plagued with walking and standing problems since last year, which has forced her to cancel a number of public engagements.

Fears of a flare-up of what royal officials are calling “episodic mobility issues” prevented her from returning to London to accept the resignation of outgoing leader Boris Johnson and appoint Truss on Tuesday.

The constitutional role – known as the hand-kissing ceremony – usually takes place at Buckingham Palace in London.

It was the first time it had taken place outside of London since 1952, when Winston Churchill met the new Queen at Heathrow Airport following the death of her father, George VI.

Meetings of the Privy Council, a type of royal advisory body dating back hundreds of years and made up of hundreds of members including religious and political leaders, are usually held monthly.

At Wednesday’s planned virtual event, Truss would have taken an oath and sworn in new cabinet ministers into their roles and also admitted new ministers as secret advisers if they weren’t already.

Last week Britain’s longest-serving monarch skipped the Highland Games, a traditional highlight of her summer in Scotland.

The recent cancellations will reignite concerns about her health.

She has scaled back her public engagements since last October after an unscheduled overnight stay in hospital due to an undisclosed illness.

She was also hit by a bout of Covid earlier this year, which she said has left her “exhausted”.