Prince Charles attended a traditional Sunday church service at Balmoral without the Queen as she continues to rest before appointing her 15th Prime Minister on Tuesday.
He was pictured on arrival at Crathie Kirk in Scotland without his beloved mother.
Cutting a lonely figure, Her Majesty stayed home amid ongoing concerns over her health.
In her on-going absence, Charles has been stepping into her role and last week attended the Braemer Gathering in her place.
The monarch cancelled a number of appointments due to worries over her mobility.
It has been suggested the Queen, a regular attendee in the past, kept away to ensure she is in the best possible health to pay a formal farewell to Boris Johnson and to welcome his replacement.
Either Liz Truss or Rishi Sunak will be announced as the new Tory leader on Monday as the outgoing PM hands back the key to No.10.
In a break with tradition, she deciding not to return to London for the ceremony and instead moved the event in the Scottish Highlands.
The last PM to be appointed away from Buckingham Palace came more than a century ago, with King Edward VII asking Herbert Henry Asquith to form a Government in Biarritz, on France’s Basque coast in 1908.
It was the latest decision to prompt fresh fears for her health.
The Queen’s traditional welcome to Balmoral Castle was axed last month.
Her Majesty had been due to attend the ceremony in Scotland on August 8, but it was cancelled - and swiftly replaced with a “small, private event”.
The sovereign was forced to miss other events this summer, including a Service of Thanksgiving at St Paul’s Cathedral and the Epsom Derby due to tiredness.
The Queen has been staying at the smaller Craigowan Lodge on her estate since arriving in Scotland on July 21.
It has recently had a “wheelchair-friendly” lift fitted ahead of the Queen’s plans to spend more time at the retreat in the Highlands.
A new security gate, intercom system and CCTV cameras have also been installed.
The event at Balmoral comes as the shameless outgoing Tory leader has refused to rule out a political comeback as he faced his final days in Downing Street.
Asked if he would rule out a comeback, he told reporters: "I think on the whole people in this country are more interested in their gigabit broadband than they are in the fate of this or that politician."
His exit was triggered by the row over the handling of allegations of inappropriate behaviour made against former deputy chief whip Chris Pincher.
Asked if he had regrets about the way the allegations were dealt with, Mr Johnson said: "All those things have to be handled carefully and sensitively and we have processes for dealing with them, and people who have complaints should raise them in the normal way."
