During The Crown’s six-season run, the hit show about Queen Elizabeth II and her family never shied from taking on the more controversial—and perhaps embellished—scenes from her life. But few portrayals brought creator Peter Morgan in for as much criticism as his looks at Prince Philip’s social life apart from his wife. In seasons two and three, the show deals with his supposed connection to the scandal surrounding John Profumo, the UK’s war secretary whose political career came to an end in 1963 after his affair with 19-year-old model Christine Keeler became public. According to a diplomatic cable seen by the Mail on Sunday, there is some historical backing for the link between Philip and what came to be known as the Profumo affair.

In The Crown’s second-season episode “Mystery Man,” Matt Smith’s Philip is shown visiting an osteopath named Stephen Ward, who treats him for a neck injury, before Ward finds himself at the center of the scandal. Later on, the queen, as played by Claire Foy, suspects that her husband may have been at a party with him. The depiction is based on the public role Ward played in the scandal. He introduced Keeler to Profumo, and to Captain Yevgeny Ivanov, a Soviet naval attaché, and the doctor was later tried on charges related to prostitution before taking his own life. According to Ward’s biographer, Anthony Summers, Ward met Phillip in the 1940s, and the prince’s good friend and cousin David, the Marquess of Milford Haven, had been especially close to Ward.

Over the weekend, the Mail reported that longtime FBI director J. Edgar Hoover sent a memo to the US embassy in London about claims made to the FBI by Thomas Corbally, an American businessman and socialite who also served as a private investigator. Corbally stated that “there was a rumor Prince Philip may have been involved with these two girls,” the June 1963 cable read. The “two girls” in question are likely Keeler and her friend, Mandy Rice-Davies, another model who was an associate of Ward.

For decades, the palace denied that Prince Philip had any connection to Ward’s activities and the scandal that ended Profumo’s career. It’s also significant that Hoover, no stranger to wild accusations and intrusive surveillance, hedges his language in the cable, calling the idea that Philip was involved a “rumor.” Still, it’s a reminder of just how much there is we don’t know about the private lives of the late monarch and her husband, just years after their deaths.