Queen Elizabeth II put duty before her own comfort despite being in “crippling pain” just two days before her death, a royal author has said.

According to Omid Scoobie, the late Queen refused to hand over her last ever duty to her eldest son Charles despite how frail she had become.

In his controversial book Endgame, Scoobie said that when Boris Johnson resigned as Prime Minister and Liz Truss took his place, royal aides suggested to Queen Elizabeth that Charles invite Truss to form a new government rather than her.

The late Queen "defiantly" refused the suggestion, which meant that the meeting took place at Balmoral in Scotland rather than in Buckingham Palace, London, where such meetings are usually undertaken.

This meeting ended up being her last ever official duty.

According to Scoobie, Elizabeth told the aides “it’s my job” and was adamant that she would host the meeting, despite the fact she had been delegating some of her duties to her eldest son within the last few months of her life.

Scoobie wrote: “After all, the heir had already stood in for his mother at the opening of Parliament four months earlier. But this was one duty the Queen—despite the crippling pain she was experiencing in private—would not step aside from.

"Her meeting with Truss was short, lasting a little under an hour, and the Queen concluded it by allowing a photograph of the two to be released—the monarch with her walking stick in her hand (a dark wood favourite that once belonged to Prince Philip) and a room-lighting smile."

The late Queen’s last public photographs were taken the same day as the meeting by Jane Barlow, PA Media photographer, who said the monarch was in "good spirits" and "very smiley" despite being frail.

She passed away two days after the meeting on September 8.