One of Queen Elizabeth II’s most trusted aides has revealed poignant details about how the grief-stricken monarch coped with the death of her beloved husband, the Duke of Edinburgh.

Prince Philip, the queen’s husband of 73 years, died on April 9, 2021, at age 99. At the funeral, Elizabeth, 95, was photographed sitting alone in the quire of St. George’s Chapel as she mourned her husband. The queen was dressed all in black, except for a diamond brooch on her left shoulder, a piece she often wore on engagements with Philip.

The ceremony was in accordance with strict social distancing rules amid the coronavirus pandemic.

Angela Kelly, the queen’s personal stylist and dressmaker who is known for being one of the reigning monarch’s closest confidants, has updated her bestselling book from 2019 titled "The Other Side of the Coin: The Queen, the Dresser and the Wardrobe." The additional chapter features new details about the royal household’s isolation during the lockdown, as well as how she was by the queen’s side following the somber service.

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Queen Elizabeth II

Queen Elizabeth II during the funeral of Prince Philip, Duke of Edinburgh, at Windsor Castle on April 17, 2021, in Windsor, England. (Leon Neal/WPA Pool/Getty Images)

"I helped her off with her coat and hat and no words were spoken," Kelly recalled in an excerpt published by Hello! magazine on Monday. "The queen then walked to her sitting room, closed the door behind her and she was alone with her own thoughts."

Kelly, whose full title is Her Majesty's Personal Adviser and Curator (The Queen's Jewelry, Insignias and Wardrobe), was a member of "HMS Bubble," or the team of staff who isolated alongside the queen and Prince Philip throughout the lockdown, the outlet shared.

The 64-year-old also detailed the mood of the palace following Philip’s death.

"The feeling among all the royal staff in the bubble at Windsor Castle was somber," she wrote. "Only a few of us were told after the family had been informed."

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Queen Elizabeth Prince Philip funeral

Queen Elizabeth II takes her seat during the funeral of Prince Philip, Duke of Edinburgh, at St George's Chapel at Windsor Castle on April 17, 2021.  (Jonathan Brady - WPA Pool/Getty Images)

When detailing the funeral, Kelly wrote: "The queen's dressers, pages, chefs, housemaids, footmen and castle attendants all stood to attention as the Duke of Edinburgh's coffin was carefully placed onto the Land Rover that he had specially designed for the day."

"You could see the expression of sadness on everyone's faces to see such a great and well-respected man making his last journey," she shared. "Their thoughts, I'm sure, were for the queen, knowing she had lost a husband and a best friend. The nation shared the grief and their hearts went out to her majesty."

Kelly said Philip’s pages and valets walked behind his coffin.

"We all felt their pain as they had worked with him for so long and we had worked alongside them. It was hard to watch our own friends saying goodbye to their amazing boss, His Royal Highness The Duke of Edinburgh," she wrote.

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Queen Elizabeth Prince Philip

Queen Elizabeth and Prince Philip with their great-grandchildren, from left, Prince George, Prince Louis, Savannah Phillips (standing at rear), Princess Charlotte, Isla Phillips holding Lena Tindall, and Mia Tindall. (Duchess of Cambridge via AP)

"I'm sure some of the prayers that were offered were by those who had never prayed before," Kelly continued. "I think those prayers were offered to keep the queen strong throughout the months to come when she would be without her husband."

For decades, Philip was a fixture of British life, renowned for his founding of the Duke of Edinburgh’s Awards program that encouraged youths to challenge themselves and for a blunt-spoken manner that at times included downright offensive remarks. He lived in his wife’s shadow, but his death sparked a reflection on his role and new appreciation from many in Britain.

Philip is survived by the queen and their four children – Prince Charles, Princess Anne, Prince Andrew and Prince Edward – as well as eight grandchildren and 12 great-grandchildren.

The Associated Press contributed to this report.