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Queen Elizabeth II’s fiercest protector, who earned the nickname "AK-47," would "take a bullet" for the monarch, royal experts claimed. This devotion later put her on a collision course with Meghan Markle during the infamous "Tiaragate."

"Angela Kelly was the real deal, a friend who would take a bullet for the queen," British broadcaster and photographer Helena Chard told Fox News Digital. "And it’s telling. Palace insiders called her ‘AK-47’ after the assault rifle because ‘people felt threatened by her.’ She was influential enough to ‘take people out’ of Buckingham Palace."

It’s been said that the late queen’s devoted dresser was no-nonsense, especially when it came to royal protocol.

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Prince Harry looking serious in a suit against a black background.

In his 2023 memoir "Spare," Prince Harry wrote about his encounter with Queen Elizabeth II's longtime dresser Angela Kelly ahead of his 2018 royal wedding. Vanity Fair correspondent Katie Nicholl revealed that the monarch's confidante earned the nickname "AK-47" behind palace doors during her time as an aide "because of her ability to take people out from the palace, where she was both revered and feared." (Chris Jackson/Getty Images)

"Meghan Markle was on a collision course as she wasn’t adhering to longstanding traditions, which ruffled many feathers among many staff members," British royals expert Hilary Fordwich claimed to Fox News Digital. "Angela was loyal to proper protocol and was the enforcer of such. Her dedication and duration of service meant she ended up shaping the presentation of the monarchy and was a gatekeeper regarding access."

"Her influence really impacted optics," Fordwich added.

Meghan Markle seated in St George's Chapel at Windsor Castle during her wedding ceremony.

Meghan Markle sits in St. George's Chapel at Windsor Castle during her wedding to Prince Harry on May 19, 2018, in Windsor, England. Members of the royal family, including Queen Elizabeth II and Prince Philip, watch the ceremony. (Jonathan Brady/WPA Pool/Getty Images)

Fordwich and Chard’s statements came after Kelly, the queen’s longtime assistant, advisor and curator, gave a rare interview to Vanity Fair correspondent and royal author Katie Nicholl.

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Kelly laid bare her close friendship with Britain’s longest-reigning monarch, who would have turned 100 on April 21, and how, during their decades-long friendship, she managed the queen’s wardrobe, including her iconic, colorful outfits.

Kelly also oversaw the queen’s collection of jewelry and ceremonial items, a responsibility that reportedly placed her at the center of a heated dispute with Prince Harry dubbed "Tiaragate."

Diana Princess of Wales wearing Spencer tiara and aquamarine diamond earrings at banquet

Diana, Princess of Wales, attends a banquet in Munich during her official tour of Germany wearing the Spencer tiara and aquamarine and diamond drop earrings. According to Prince Harry, he had suggested that Meghan Markle wear the Spencer tiara on their wedding day. (Tim Graham Photo Library/Getty Images)

Nicholl wrote that ahead of her wedding to Harry in 2018, Meghan was presented with a selection of tiaras for the occasion. Although the former American actress was drawn to an emerald piece, Nicholl noted it was ultimately deemed unsuitable for her big day.

Prince Harry and Meghan Markle wearing their wedding attire after getting married at Windsor.

Meghan Markle, a former American actress, became the Duchess of Sussex when she married Prince Harry, a British prince, in 2018. (Ben Stansall-WPA Pool/Getty Images)

"While Meghan was happy with the Queen Mary Diamond Bandeau that the queen had offered her instead, tensions arose again when Meghan was told by Kelly that she was not allowed to use the tiara for a trying-on session with her hairdresser ahead of the wedding day, reportedly causing Harry to ‘erupt’ at Kelly," wrote Nicholl.

A palace source told Nicholl that the queen refused to let the tiara leave the palace two weeks before the wedding.

Queen Elizabeth II looking on during Prince Harry and Meghan Markle wedding in Windsor

Queen Elizabeth II looks on during the wedding of Prince Harry to Meghan Markle on May 19, 2018, in Windsor, England. (Jonathan Brady/WPA Pool/Getty Images)

"[Angela] often took a bullet for the queen, but this time Harry really went for [her]," a source claimed to Nicholl. "Harry was giving Angela hell."

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Angela Kelly walking outside the Goring Hotel in London

Angela Kelly leaves the Goring Hotel after attending a Christmas lunch hosted by the queen for her close staff members in London on Dec. 11, 2018. (Max Mumby/Indigo/Getty Images)

Royal expert Ian Pelham Turner told Fox News Digital that Kelly wasn’t afraid to face anyone who challenged her. But that also reportedly put her in direct conflict with the Duke and Duchess of Sussex.

"With the nickname ‘AK-47,’ she guarded the sacred values of the queen’s collection, including the precious jewels, clothes and hats," he explained.

Queen Elizabeth II talking to guests at a reception at Buckingham Palace

Queen Elizabeth II talks to guests at an evening reception for members of the Diplomatic Corps at Buckingham Palace in London on Dec. 11, 2019. (Victoria Jones/WPA Pool/Getty Images)

"She guarded these areas with a renowned intensity, making her the queen’s fashion bodyguard. There were many rumors surrounding how the royal household never tried to oppose or impose any strategies on her. She was regarded as the feminine equivalent of a Rottweiler, with a bite if she was questioned."

Queen Elizabeth II seated with Anna Wintour, Caroline Rush, and Angela Kelly at Richard Quinn runway show

Queen Elizabeth II sits with Anna Wintour, Caroline Rush, chief executive of the British Fashion Council, and royal dressmaker Angela Kelly as they watch Richard Quinn's runway show and present him with the inaugural Queen Elizabeth II Award for British Design at London Fashion Week's BFC Show Space on Feb. 20, 2018, in London. (Yui Mok/Pool/Getty Images)

However, nothing prepared Kelly to reportedly go toe-to-toe with the boss’s grandson, who was just as protective of his future wife. A palace source told Nicholl that she "was very much caught in the middle."

"At one point, [Harry] said, ‘Let me tell you, I don’t agree with you talking to my grandmother about this,’" Nicholl wrote. "Angela was in tears and went to the queen, saying she couldn’t take it anymore. Eventually, the queen said, ‘He can’t have it; I’ll deal with him. We’re having enough trouble with this wedding.’"

Queen Elizabeth, Meghan Markle and Prince Harry in formal wear standing on the balcony of Buckingham Palace.

From left: Queen Elizabeth II, Meghan, Duchess of Sussex and Prince Harry, Duke of Sussex watch a flypast to mark the centenary of the Royal Air Force from the balcony of Buckingham Palace on July 10, 2018, in London, England. The couple stepped back as senior royals in 2020. (Max Mumby/Indigo/Getty Images)

"People still question how Kelly had the queen’s ear, viewing her as a mere servant," said Chard. "Kelly’s power wasn’t ceremonial. She controlled access to the queen daily, and Queen Elizabeth backed her. Kelly put her heart and life into her work. She ran a tight, tidy ship, never leaving a stone unturned. She cared deeply for Queen Elizabeth, instilling confidence, protecting royal protocol and hierarchy, which was seen as an obstruction to some. However, it was given the queen’s approval."

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Angela Kelly wearing Royal Victorian Order medal at Buckingham Palace

Angela Kelly, personal dresser to Queen Elizabeth II, wears her Royal Victorian Order medal after it was presented to her by the queen at Buckingham Palace on Nov. 16, 2012, in London. (John Stillwell/WPA Pool/Getty Images)

"Queen Elizabeth declared that the tiara in question ‘was not a toy,’" Fordwich claimed. "Angela was loyal to proper protocol and was the enforcer of such."

Fox News Digital reached out to Buckingham Palace for comment.

Prince Harry in a black suit holding Meghan Markle's hand at Windsor Castle

The Duke and Duchess of Sussex depart following their wedding in St. George's Chapel at Windsor Castle on May 19, 2018, in Windsor, England. (Owen Humphries/WPA Pool/Getty Images)

Harry, 41, shared a different account of "Tiaragate" in his 2023 memoir, "Spare." He wrote that Meghan was initially set to wear the Spencer tiara, previously worn by his mother, the late Princess Diana. The queen then asked if Meghan wanted to wear a tiara from her collection.

Copies of Prince Harry's book Spare displayed on a table at Daunt Books in London

Copies of "Spare" by Britain's Prince Harry, Duke of Sussex, are displayed at Daunt Books on Marylebone High Street in London on Jan. 10, 2023.  (Justin Tallis/AFP/Getty Images)

"She offered us access to her collection of tiaras," Harry wrote, as quoted by People magazine. "She even invited us to Buckingham Palace to try them on. 'Do come over,' I remember her saying."

Harry said that the queen herself suggested that Meghan practice putting on the heirloom with her hairdresser. "It's tricky, and you don't want to be doing it for the first time on the wedding day," said the queen, he recalled.

Queen Elizabeth II greeting Kazakhstan President Nursultan Nazarbayev at Buckingham Palace

Queen Elizabeth II died in 2022. She was 96. (Chris Jackson/WPA Pool/Getty Images)

Harry claimed that Kelly made it difficult to arrange. Not only did she become unresponsive to the couple, but she eventually told them that the tiara needed a "police escort" to leave the palace. When Harry agreed to arrange for an orderly and a police officer to do so, Kelly "inexplicably" told him, "can’t be done," the book claimed. 

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Prince Harry and Meghan Markle riding in a carriage at Windsor Castle

Prince Harry, Duke of Sussex, and Meghan, Duchess of Sussex, begin their carriage procession in the Ascot Landau Carriage after their wedding ceremony at St. George's Chapel, Windsor Castle, on May 19, 2018. (Gareth Fuller/AFP)

"I considered going to Granny, but that would probably mean sparking an all-out confrontation, and I wasn't quite sure with whom Granny would side," Harry wrote. "Also, to my mind, Angela was a troublemaker, and I didn't need her as an enemy."

Chard noted that with Meghan being a newcomer to the British royal family’s tight circle, there were bound to be obstacles with protocol.

Prince Harry and Meghan Markle walking hand in hand at Sydney Opera House

The Duke and Duchess of Sussex stepped back as senior royals in 2020, citing the unbearable intrusions of the British press and a lack of support from the palace. (Paul Edwards/Pool/Getty Images)

"The ‘Tiaragate’ controversy arose as Hollywood and palace hierarchy clashed," said Chard. "Sources have also shared whispers of other family tensions. However, sources have only offered glowing reports of the queen and Angela Kelly’s relationship."

Princess Eugenie of York arriving at St. George's Chapel in Windsor

While the emerald tiara in question wasn't identified, Princess Eugenie wore the Greville Emerald Kokoshnik Tiara on her wedding day in 2018. (Andrew Matthews/WPA Pool/Getty Images)

Fordwich said that Kelly earned her "clever" nickname with good reason. She was "sharply effective" and "an empowered gatekeeper and protector" of the queen.

"Angela earned her place of privilege with the immense trust shown by the queen due to her dedication and loyalty, two characteristics that are critical to serving the royals," said Fordwich. "Angela also, rather uniquely, earned personal trust through some special talents, such as breaking in shoes for the queen, updating her look, which was successfully welcomed, and becoming a trusted confidante during the COVID lockdown."

Queen Elizabeth II wearing diamond rose brooch at Buckingham Palace launch event

According to Vanity Fair, Angela Kelly encouraged Queen Elizabeth II to wear more colorful ensembles. (Max Mumby/Indigo/Getty Images)

"Although from different backgrounds, the late queen and Angela Kelly held similar values, with duty being their priority," said Chard. "They forged an unbreakable bond. Queen Elizabeth loved Kelly’s pragmatic bluntness and viewed her as an incredibly loyal friend.

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Angela Kelly standing inside Westminster Abbey during Queen Elizabeth II's state funeral

Angela Kelly is seen during the state funeral of Queen Elizabeth II at Westminster Abbey in London on Sept. 19, 2022. (Chris Jackson/Getty Images)

"As Kelly ascended the hierarchy, she gained seniority and status. However, this led to many feeling somewhat jealous and threatened by her access to Queen Elizabeth."

The Duke and Duchess of Sussex stepped back as senior royals in 2020 and moved to California.

Kelly’s role came to an end after the queen died in 2022. She quietly stepped away from royal duties and retired from public service.