She also kept the bombshell programme a secret from the Queen, according to the second part of ITV’s The Diana Interview: Revenge Of A Princess. Diana revealed to BBC journalist Martin Bashir that “there were three people in this marriage, so it was a bit crowded” during the 1995 interview that sent shockwaves across the world.
According to ITV’s documentary, Diana was asked when the interview should be announced.
Editor Ian Corcoran said: “Martin suggested that we asked Princess Diana.
“He slipped out of the room to phone her and a while later he came back in, he said she had suggested a date which just happened to be Prince Charles’ birthday.”
Richard Kay, a friend of Princess Diana’s, added: “It may be that Bashir and co said, ‘Well, we want to announce it on the 14th November and she would have said, ‘Oh, that’s my husband’s birthday, why not?'”
Asked whether she had stipulated that she wanted it revealed on his birthday, Mr Kay said: “Well, I would have thought that was typically mischievous Diana.”
According to the documentary, Diana reportedly believed she was under surveillance from the secret services after her separation from Prince Charles.
Diana’s biographer, Andrew Morton, said: “Diana certainly was very concerned about the Secret Services, about MI5, about MI6.
“There were bizarre things going on inside the households of the Prince and Princess of Wales.
Mr Burrell said: “The princess did suspect that she was being followed, that she was being watched. She was under surveillance, whether it was phone hacking or spying.
“There were occasions when we pulled up the floorboards and unscrewed the end of the telephones to see if there are any listening devices.”
He added that she was not paranoid, but “concerned”.
But Diana’s brother, Earl Spencer, accused Mr Bashir of producing fake documents to obtain the trust of her family.