The appointment of new prime ministers is one of the Queen’s key constitutional duties, and the latest she had been able to undertake with modifications.
She has already started receiving ambassadors via video call and has held virtual Privy Council meetings during the pandemic.
This year, she delegated the State Opening of Parliament to two of her Counsellors of State through the issue of Letters Patent, allowing her two heirs – the Prince of Wales and the Duke of Cambridge – to perform the duty for her.
On Friday night, one constitutional expert told The Telegraph that Her Majesty could have asked them to stand in for her again, explaining that: “Counsellors of State can represent the Queen in all respects.”
The likely change in venue to Scotland would require the incoming prime minister and his or her officials to fly to Balmoral and return to Westminster in a short round trip, for what has usually amounted to a short welcome from the Queen and a photograph to mark the occasion.
A source on the Truss leadership campaign said: “Of course she will [go to Balmoral]. Any prime minister would go to wherever the Queen was. “
A Sunak campaign source said: “The prime minister serves Her Majesty. Meeting her di lei is part of becoming PM and part of your duty and your service. “
Downing Street could not confirm whether Mr Johnson was still planning to attend the annual Braemer Games in Scotland with the Queen, allowing him to spend his last weekend as Prime Minister at Balmoral in advance of his formal resignation.
Buckingham Palace declined to comment.