Prince William, Harry’s former royal mentor reveals mother’s secret MI5 past after decades of silence

Jamie Lowther-Pinkerton reveals how his mother Sue’s remarkable life inspired his debut novel, "Beyond the Edge of Light."

Jamie Lowther-Pinkerton grew up knowing his mother had led an "amazing life." But there was one chapter she rarely spoke about.

After World War II, Sue Lowther-Pinkerton joined MI5 and worked in British intelligence during the Cold War. But she revealed little to her children about that part of her past.

Decades ago, while watching a documentary with her children, Sue let something slip.

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Prince Harry, Private Secretary Jamie Lowther-Pinkerton and Prince William at the 10th anniversary memorial service for Diana, Princess of Wales at Guards Chapel at Wellington Barracks on Aug. 31, 2007, in London. (Tim Graham Photo Library via Getty Images)

"We were watching a documentary one afternoon about 30, 40 years ago," Lowther-Pinkerton recalled to Fox News Digital. "And there was a thing called the ‘Cambridge spy ring,’ which were Soviet agents who had infiltrated the British system. And there was a great mystery about who the fifth man was. And up pops the documentary maker saying, ‘Well, it could be Sir Roger Hollis.’"

Jamie Lowther-Pinkerton stands behind Prince William during a Remembrance Day service at Camp Bastion in southern Afghanistan. (PA Images via Getty Images)

Hollis served as director general of MI5 from 1956 to 1965. He later became the subject of allegations that he had secretly worked for the Soviet Union, claims that were investigated but never proven.

Sue didn't hesitate.

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"My mother, without missing a knitting stitch, said, ‘Absolute nonsense. He was a total gentleman and a patriot.’"

"[My sister and I] both looked at her sideways as if she was completely mad," Lowther-Pinkerton said. "I tried to get more out of her, but she was of that generation who quite rightly just didn’t want to talk about it."

Sue Lowther-Pinkerton died on Dec. 24, 2023. (Courtesy of Jamie Lowther-Pinkerton)

Lowther-Pinkerton said he was in his mid-20s before he and his older sister learned of their mother's intelligence career.

"Beyond the Edge of Light" by Jamie Lowther-Pinkerton is available now. (Penguin Random House)

MI5, formally known as the Security Service, is Britain's domestic intelligence agency. According to MI5's official history, the agency traces its origins to the Secret Service Bureau, established in 1909. The bureau was later divided into domestic and foreign sections that developed into MI5 and MI6.

That rare glimpse into his mother's past stayed with Lowther-Pinkerton for decades. Now, her extraordinary life has helped inspire his novel, "Beyond the Edge of Light," a wartime love story. Its central character, Missie, a rebellious young woman who joins military intelligence, was inspired by Sue, who died in 2023 at age 99.

Jamie Lowther-Pinkerton. (Courtesy of Jamie Lowther-Pinkerton)

Long before Sue entered the secretive world of MI5, she had already lived a life of adventure.

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ATS women take a break at a 3.7-inch anti-aircraft gun site at Wormwood Scrubs in London on Oct. 22, 1941. (Imperial War Museums via Getty Images)

As World War II unfolded, she worked on NAAFI (Navy, Army and Air Force Institutes) vans serving tea and food to troops and painted white lines on roads before she was old enough to enlist. In 1942, she joined the Auxiliary Territorial Service, the women’s branch of the British Army.

Princess Elizabeth, as junior commander in the ATS, inspects the Motor Transport Training Centre on May 1, 1945. (Mirrorpix via Getty Images)

She was later posted to the Royal School of Artillery at Larkhill, where she drove gun limbers — vehicles used to transport artillery equipment — across firing ranges. Because the work was considered dangerous, she received an additional four pence a day.

After the war, her work took her into an even more secret world.

Jamie Lowther-Pinkerton's late mother Sue. (Courtesy of Jamie Lowther-Pinkerton)

"She went into Secret Service," Lowther-Pinkerton said. "So she joined MI5, which was the equivalent. It's a sort of mixture between the FBI, I think, and the CIA. And she was in that during the Cold War."

Sue's intelligence career began even before she joined MI5. According to The Telegraph's obituary, she worked in Army intelligence in Singapore after leaving the military in 1948. There, she was entrusted with secret communications concerning HMS Amethyst's planned 1949 breakout from China's Yangtze River.

One of the secret MI5 files released for the first time to the Public Records Office in Kew, London. (PA Images via Getty Images)

After returning to Britain in 1951, Sue joined MI5 and worked at Leconfield House. But she remained fiercely guarded about what she did there — even with her son, who would go on to serve in the Irish Guards and the Special Air Service (SAS).

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Jamie Lowther-Pinkerton guided Prince William and Prince Harry through their entry into the armed forces. (Indigo/Getty Images)

Growing up, Lowther-Pinkerton heard stories of his mother being raised in India and eventually getting "kicked out of every educational establishment she ever went to." He described his mother, who didn’t see her parents for years on end, as "incredibly wild."

Sue received 11 marriage proposals before Lowther-Pinkerton’s father, Anthony Hull Lowther-Pinkerton, or "Rumpty," a "great big Anglo-Irishman" who was "everybody’s life and soul of the party," wooed her.

Jamie Lowther-Pinkerton attends the annual Chelsea Pensioners Founders Day Parade at Royal Hospital Chelsea on June 9, 2011, in London. (Indigo/Getty Images)

"[They] had all of us children and went to live in Suffolk, which is where I grew up," he said. "... [My father] could go up and down in moods. And my mother just ... kept the family going absolutely on the straight and narrow through the middle with her calmness really. That was the great thing about her. Nothing fazed her."

Kate Middleton attends the Sovereign's Parade at Sandhurst Military Academy in Surrey, England, on Dec. 15, 2006, accompanied by Prince William's private secretary Jamie Lowther-Pinkerton. (Tim Graham Photo Library via Getty Images)

"I remember one occasion when my father got really down in the dumps," he recalled. "She made really good roast potatoes for lunch. And she’d obviously had enough. She got this potato, and she flung it down the dining room table with [my sister] Sarah and me on either side thinking, ‘My goodness, what’s going to happen now?’

"And she hit my father clean between the eyes. My father was literally crying with laughter within about 20 seconds. She just knew. It wasn’t always roast potatoes, but she knew how to deal with him."

Prince Harry walks with his private secretary, Jamie Lowther-Pinkerton, after attending a service of morning prayer at Christ Church Cathedral on March 4, 2012, in Nassau, Bahamas. (John Stillwell-Pool/Getty Images)

According to Sue’s obituary, she remained in MI5 until leaving in 1956 to start a family. For almost 50 years, she helped organize the annual Poppy Appeal, a fundraising campaign supporting veterans, active-duty service members and their families. For several decades, she also delivered Meals on Wheels to remote cottages and farmsteads.

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Queen Elizabeth II and Queen Elizabeth The Queen Mother in 1990. (John Shelley Collection/Avalon/Getty Images)

Lowther-Pinkerton’s life also took an unexpected turn. He went on to serve in the royal household as an equerry to Queen Elizabeth the Queen Mother.

"She was an absolute joy to be with," he said with a smile. "She was like everybody’s favorite granny. She had a bolt of steel running down her spine, so nothing fazed her."

Glamis Castle turrets in Forfar, Angus, Scotland. (Andrew Holt/Construction Photography/Avalon/Getty Images)

"She was the daughter of a Scottish girl who grew up in Glamis Castle. When she was 15, her favorite brother was killed in the trenches in the First World War. And Glamis Castle was given over, at least a part of it, to being a military hospital for wounded soldiers coming back from the First World War."

"Like my mother, she had an incredibly sharp memory," he continued. "I remember sitting with the Queen Mother at lunch and talking about the war. It was enlightening. And she had a wonderful sense of humor. I absolutely adored her."

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The gig came with perks. Lowther-Pinkerton laughed when reminded that he would mix the martinis for her parties. He previously told People magazine the drinks were seven parts gin with "a whiff of vermouth." According to the outlet, he would top her "decent-sized drink" with ice.

Prince William, left, and Prince Harry are greeted by Jamie Lowther-Pinkerton as they arrive for the unveiling of a statue of their mother, Princess Diana, at The Sunken Garden in Kensington Palace, London, on July 1, 2021, which would have been her 60th birthday. (Pool/AFP via Getty Images)

Lowther-Pinkerton served as a private secretary to Prince William, Prince Harry and later Kate Middleton, from 2005 to 2013, People reported. He served as a mentor for the princes. His son Billy was a page at William and Kate’s wedding.

The couple later asked Lowther-Pinkerton to be a godfather to their eldest son, Prince George.

Kate Middleton hands Jamie Lowther-Pinkerton bunches of flowers during a walkabout after attending the naming ceremony and service of dedication of the Atlantic 85 lifeboat Hereford Endeavour at Trearddur Bay Lifeboat Station at Anglesey on Feb. 24, 2011 in Bangor, Wales. (Indigo/Getty Images)

Lowther-Pinkerton said the remarkable women in his life have inevitably influenced his writing. "It all seeps in," he said.

His mother, however, remains at its heart.

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Jamie Lowther-Pinkerton and Prince William watch the parade and flypast during the Battle of Britain 70th Anniversary Service at Westminster Abbey on Sept. 19, 2010, in London. (Indigo/Getty Images)

"Somebody of strength, somebody who has their own opinions and is not going to be pushed around," he said of the legacy he hopes Sue leaves with readers.

Stephanie Nolasco is an Entertainment Reporter for Fox News Digital.

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