The Princess of Wales moved the nation this year, when the royal bravely revealed in March that she had been diagnosed with cancer.
Kate shared the news in a video, filmed by BBC Studios, where she was seen sitting on a wooden bench wearing a striped jumper. In his new book, New King, New Court, which is a biography about King Charles, biographer Robert Hardman revealed a previously unseen part of the royal's emotional statement.
After writing about the social media furore that had erupted following Kate's absence from public, Robert noted how the video "shook" many.
"It had certainly not been captured on a family mobile phone," he wrote. "The Princess had been filmed by a cameraman from BBC Studios Events Productions, the same team which filmed the Coronation and the late Queen's funeral."
However, when it came to the official transcript, part of this went against the standard royal protocol. Robert revealed: "The words, however, were entirely the Princess's own. Even the formal transcript issued by the Palace broke with protocol.
"It was attributed not to 'HRH The Princess of Wales', but to 'Catherine, The Princess of Wales', a tiny point to most people but a noteworthy one in an institution bound to a correct way of doing things."
Robert also noted the presence of daffodils in Kate's message, with the flowers having been seen in the late Queen's video message to the nation during the coronavirus pandemic.
The mum-of-three has since completed her chemotherapy treatment, however, she is slowly easing herself back into work.
The royal is expected to make an appearance this weekend to mark remembrance services held across the nation including Festival of Remembrance at the Royal Albert Hall on Saturday and the Cenotaph on Sunday.
It, however, remains unclear as to whether Queen Camilla will feature at the events after she contracted a chest infection and started recovering at home.
On Tuesday afternoon, a Palace spokesperson said: "Her Majesty The Queen is currently unwell with a chest infection, for which her doctors have advised a short period of rest.
"With great regret, Her Majesty has therefore had to withdraw from her engagements for this week but she very much hopes to be recovered in time to attend this weekend’s Remembrance events as normal. She apologises to all those who may be inconvenienced or disappointed as a result."