Across the season Diana grows increasingly isolated from the rest of the Royal Family, and begins to fear that her conversations are being listened in to.
This comes to a head in episodes 7 and 8, when Martin Bashir is seen forging documents which make Diana believe further that those around her are working against her.
But was Diana's phone really tapped and if so, by who? Read on for everything you need to know about this storyline in The Crown season 5.
What happens with Diana's phone in The Crown season 5?
In The Crown season 5 episode 2, called The System, Diana works with her friend James Colthurst to send confessional tapes about her life and her treatment by the Royal Family to biographer Andrew Morton. During this time she grows ever fearful that she is being watched and listened into.
When Andrew's house is broken into and his office ransacked, and James is knocked off his bike, Diana worries that the two are linked and part of a targeted attack.
She has her office scanned for bugs and when the phone rings she tells James: "I'm not answering that. I'm not speaking on this thing again, ever. I heard a click on our line this morning. On this end."
This fear that her phone has been tapped and her rooms bugged carries through the season. In episode 7, called No Woman's Land, Diana speaks with William on the phone once he has started at Eton.
At one point a clicking can be heard on the phone, to which Diana asks "What was that?". She says that she "heard a click" and asks William if he heard it too, to which he replies "No". She tells him: "We have to be careful. There are people out there who want to listen in on our calls. There are bugs everywhere."
After the call ends Diana hears further clicking on the line. She asks "Hello?", but hears no response.
Later she speaks with her Private Secretary Patrick, and tells him: "I'm not imagining it Patrick. I hear clicks on the line all the time."
Patrick replies: "It's my understanding that every call, incoming and outgoing, goes through the main palace switchboard, making it very difficult indeed to set up a tap."
However, Diana seems unconvinced, simply saying: "Yeah, but not impossible."
Diana later affirms in a meeting with her brother that she believes it is the palace and the wider establishment that is spying on her, telling him: "They've been spying on me for years. They're all in on it. That's why I got rid of my personal protection officers."
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It's this fear that journalist Martin Bashir exploits to get her to agree to an interview with Panorama, telling her own side of the story.
Was Diana's phone really tapped and if so, by who?
In reality we do know that Diana's phone calls were reportedly listened into on at least one occasion, the first of which is in what came to be known as Squidgygate.
The incident, which is not depicted in The Crown season 5, saw a recording of an intimate conversation on a Sandringham landline, between Diana and James Gilbey, leaked to the press, reportedly by two separate amateur radio eavesdroppers.
Later enquiries and analysis of the tape recordings suggested these may have been made by GCHQ and passed to the supposed eavesdroppers, although this was never conclusively proved.
Ken Wharfe, who acted as Diana's bodyguard until 1993, told her inquest that it was his belief that "this internal recording was probably made by GCHQ… they probably had a good reason for doing it.
"For some unknown reason this conversation is released on a loop to allow (radio hams) Cyril Reenan and Jane Norgrove to pick them up."
Another incident was reported by The Observer, who said that said that the CIA was listening in on Diana in the hours before she died, without British intelligence's permission.
Beyond this there has never been confirmation that Diana's phone was tapped for a longer stretch, but we do know that she was reportedly concerned about the idea that it might have been.
In 2007, one of Diana's former Private Secretary, Michael Gibbins, said that she had grown fearful that her phone had been tapped before her death in 1997.
When asked whether it was a concern of hers, Gibbins said: "She never expressed that concern but her actions were such, in terms of changing her telephone number, that it was clear that that was a concern to her, yes."
Meanwhile Andrew Morton, who wrote the 1992 biography of Diana entitled Diana: Her True Story, wrote in his 2011 book William and Catherine that Diana had made jokes about the subject while on phone calls.
Morton said in the book: "When Diana, Princess of Wales talked on the phone – which was often – midway through a conversation she would suddenly say, 'Hello boys, time to change the tape.'
"It was a joke with an uncharacteristically bitter twist. The Princess believed not only that the Palace was conspiring against her, but that the security forces were routinely tapping her telephones."
The Crown season 5 will be released on Netflix on 9th November 2022 and you can watch seasons 1-4 right now. Sign up for Netflix from £6.99 a month. Netflix is also available on Sky Glass and Virgin Media Stream.
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