EXCLUSIVE: Prince Philip's Other Woman Revealed — As It Emerges Playboy Duke Didn't Spend End of His Life With Queen Elizabeth

Devoted Queen Elizabeth II was brutally betrayed by husband Prince Philip when the once-dashing consort retreated to a remote cottage near the end of his life and enjoyed the company of a much younger countess, sources told RadarOnline.com.

"They were very close," a royal insider revealed, referring to Philip's scandalous friendship with Penelope Knatchbull, Countess Mountbatten of Burma, who is known as Penny. "She spent more time with him than his wife."

The beautiful aristocrat, who's 32 years younger than Philip and the wife of his first cousin once removed, was reportedly given the nickname "And Also" by staffers because whenever the notorious skirt-chaser was creating an invite list for a royal party, he'd always end with "and also Penny."

Philip's secret arrangement is laid bare in the book Queen Elizabeth II by Hugo Vickers, who revealed how the handsome Duke of Edinburgh quit his royal duties in August 2017 and began living at Wood Farm at the Sandringham estate, while the monarch lived at Windsor Castle roughly 130 miles away.

"The queen let the duke do exactly as he pleased," Vickers wrote.

"He enjoyed his carriage-driving, read voraciously and painted a little. From time to time, the queen went up by train to Norfolk to stay the weekend. Once again, she gave him a loose rein. In a sense, they had separated."

Philip died on April 9, 2021, just two months before his 100th birthday.

During her lifetime, Elizabeth, who passed away at age 96 in 2022, had publicly ignored talk that her husband was cheating. She even brushed off such rumors when they first swirled shortly after their wedding on Nov. 20, 1947.

"But that doesn't mean she wasn't hurt – or furious – over his flings," the insider told RadarOnline.com. "But she'd never show it. She refused to let herself, and the monarchy, be humiliated."

Insiders claimed the queen kept a secret dossier with the names of women in her husband's life.

Sources said Elizabeth hit the roof in 2020 when royal biographer Ingrid Seward released the book Prince Philip Revealed, which claimed he fathered two love children with his longtime pal, French actress Helene Cordet, who died in 1996.

The duke has been publicly linked to at least 13 women, including the late Susan Barrantes – the twice-married mother of his disgraced son Andrew Mountbatten-Windsor's ex-wife, Sarah Ferguson.

"Prince Philip usually made a beeline for the prettiest girl on the dance floor," wrote Sarah's father, Ron Ferguson, in his memoir, The Galloping Major: My Life and Singular Times, which was released nine years before the former soldier's death in 2003.

"He certainly found Susie's company much more enticing than mine."

Philip's other reported conquests include Hollywood sexpot Zsa Zsa Gabor, actresses Jane Russell and Pat Kirkwood, the queen's cousin Princess Alexandra, and a bevy of other beauties.

However, Elizabeth may have gotten her revenge.

Royal biographer Andrew Lownie – author of the bestseller Entitled: The Rise and Fall of the House of York – has said that he believes the queen's son Andrew may have actually been fathered by her longtime horse racing manager, Lord Porchester – and not the duke.