The marriage that never stood a chance: Prince Charles and Princess Diana

The ceremony was held at St Paul’s, the only cathedral big enough to accommodate the couple’s 3,500 guests, including most of the crowned heads of Europe, the French president François Mitterand and US first lady Nancy Reagan.

Tens of thousands of loyal subjects lined the streets as members of the Household Cavalry, in their Ruritanian get-up of scarlet tunics and gleaming breastplates, with plumed helmets bobbing, trotted alongside the Glass Coach carrying Diana to the church. 

And at St Paul’s the blushing bride was escorted up the aisle by her father Earl Spencer, her 25ft train of ivory taffeta and antique lace in her wake. 

In short, it was the sort of ceremony befitting the celebration of a great love between a latter-day Romeo and Juliet. But, as we now know, nothing could have been further from the truth. 

As the princess revealed from beyond the grave in 25-year-old fi lm footage shown for the first time in the UK in Sunday’s night’s Channel 4 documentary Diana In Her Own Words, she and Charles had met only 13 times before they plighted their troth on July 29, 1981. 

The truth is this was a marriage of convenience for a future king in need of an heir and a spare because Camilla Parker Bowles, the love of his life, had got spliced to another man. 

The warning signs had been there from the very start. When the newly engaged couple were famously asked if they were in love, Diana the 19-year-old ingenue responded at once with, “Of course!” But Charles, perhaps conscious of a certain someone watching his every move for signs of emotional betrayal, said: “Whatever ‘in love’ means.”  

Monarchists attributed his equivocation to royal reserve but others saw it for was it was: semantic leakage of his true feelings. Diana certainly did. 

As she said in the Channel 4 recordings filmed by her voice coach Peter Settelen: “That threw me completely. I thought that a strange question and answer. God, absolutely traumatised me.” 

Once married life got under way, sex was at a premium. Diana told Settelen that things happened between the sheets “sort of once every three weeks”.

She added: “It was odd, very odd. But it was there, then it fizzled out about seven years ago, six years ago, well, seven because Harry was eight. 

“Instinct told me it was just so odd. I don’t know, there was just no requirement for it from his case.” 

Meanwhile, the spectre of her love rival was ever-present. Even on her big day at St Paul’s Diana’s eyes had raked over the congregation as she walked up the aisle in search of her romantic nemesis before settling on a blonde in a “pale grey, veiled pillbox hat”: Camilla. 

As she was to tell Martin Bashir in her bombshell Panorama interview some years later: “There were three of us in this marriage so it was a bit crowded.” When she confronted Charles, he allegedly replied: “I refuse to be the only Prince of Wales who never had a mistress.” 

The Channel 4 broadcast coincided with fresh revelations from an unnamed BBC cameraman who Diana hired in March 1997, five months before her death. In seven sessions they recorded 12 hours of her impassioned reminiscences as she off-loaded her anger at the Royal Family and Charles in particular. 

Naturally Camilla got it with both barrels. According to the cameraman, Charles would call Camilla for “phone sex” while sitting on the toilet. 

“She caught Charles and Camilla in flagrante after listening in to his phone calls,” he says. In one Charles was sitting on the toilet seat when she caught him.” He says she claimed, “Camilla was the raunchier of the two.” 

At her wits’ end, Diana decided to consult “the top lady”, her mother-in-law the Queen: “I asked her, ‘What do I do? I’m coming to you, what do I do?’” to which the Queen replied: “I don’t know what you should do, Charles is hopeless.” 

Not that Diana was living the life of a nun while her husband played away. In the tapes she admits to falling in love at the age of 24 with “someone who was part of all this” but once her infatuation was discovered “he was chucked out and then he was killed”. This is believed to be a reference to her personal protection officer Barry Mannakee who died in a motorcycle accident three weeks after being sacked. 

Her relationship with Mannakee was never consummated, but a few years after the birth of Harry, Diana had embarked on a full affair with James Hewitt, a Household Cavalry captain. “I was a rebel,” she told Settelen.

“I always did the dares. I always did the opposite of everyone else. I wasn’t academically interested at all, I just wanted to be with people and have fun and look after people. But the rebel thing was always there. It was underlying. It didn’t come out. Or they didn’t see it.” 

Until it was too late.