Princess Diana tragically passed away in Pont de l’Alma Tunnel in Paris, France on August 31, 1997.

That afternoon, she and Dodi Fayed had made their way to the Ritz Hotel in the heart of the city.

Once settled into the Imperial Suite at the five-star hotel, the princess phoned an anxious Prince William who revealed he had been asked to take part in a photocall at Eton to mark the start of his third year.

The photocall was part of a deal between the press and the palace, according to Diana’s biographer Andrew Morton.

Writing in the book Diana: Her True Story – In Her Own Words, Morton explained: ‘In return for leaving the young princes in peace, the media would be given occasional official photo opportunities.

‘William was worried that there was a danger this his younger brother, Prince Harry, was being overshadowed.

‘It was a concern shared by Diana,’ he added.

‘As she had her hair done at the Ritz, she doubtless pondered on this conversation, her last with her eldest son.’

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Princess Diana and Dodi Fayed in the lift of the Ritz hotel hours before they passed away

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Diana arrives at the Ritz for dinner after spending a few hours at Dodi’s apartment

In the meantime, Dodi had left Diana to speak to her worried son and visited a nearby jewellery store called Alberto Repossi.

There the British-Egyptian millionaire picked up the ‘Tell Me Yes’ ring that he had sent to be altered.

Diana had chosen the ring, estimated to be worth around £11,000, while shopping with Dodi in Monte Carlo during their Mediterranean cruise.

Dodi had also spoken to the Saudi Arabian millionaire, Hassan Yassin, the brother of his stepfather, who happened to be staying at the Ritz that same evening.

‘It’s serious. We’re going to get married,’ Dodi allegedly told him. Hassan later recalled: ‘I was happy for him, for both of them.’

Later that evening, Dodi and Diana had planned to visit his apartment on the Champs-Élysées before having supper at Le Benoit restaurant near the Pompidou Centre.

‘Was it here that Dodi planned to make a declaration of love, present the ring, which was later found in his apartment, and ask for Diana’s hand in marriage?’ Morton penned.

‘Certainly their last conversations with confidants that night suggested that their brief affair was about to take a significant and perhaps permanent course.

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Charles, Diana and Harry watch as Prince William signs the Entrance Book at Eton College in 1995

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The princess made a point to have her boys pictured together so they could ‘share the spotlight’, according to her confidante Richard Kay

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In her final hours, William called his mother to say that a solo photocall at Eton had been arranged

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Both Diana and William were worried that was worried ‘his younger brother, Prince Harry, was being overshadowed’

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William and Harry pictured at Westminster Abbey for the funeral of Princess Diana on September 6, 1997

As well as William, one of the last people Diana called on the night of her death was none other than Richard Kay, the Daily Mail’s Editor at Large.

He recalled that Diana was supposed to be back in London that night but bad weather had delayed her for 24 hours.

‘The delay meant she would not arrive back at Kensington Palace until Sunday,’ Richard explained, ‘when William and Harry were due to join her after their three-and-a-half weeks with Prince Charles and the royals at Balmoral.

‘Without doubt, she would have been utterly baffled at the criticism earlier this summer that somehow she had abandoned the boys to go off with Dodi.

‘It had been carefully arranged that they would spend part of the summer with their father and an equal amount of time with her,’ Richard wrote in an article for the Daily Mail to mark the 20th anniversary of Diana’s death.

Richard also remembered Diana’s ‘dismay’ that William was ‘expected to face a photocall at Eton at the beginning of the forthcoming term without Harry’.

He wrote: ‘Diana had established that, wherever possible, the boys should share the spotlight.

‘It was a deal that Charles faithfully kept to throughout the following years.’

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Just over a year after the first anniversary of his mother’s death, Harry arrives for his first day at Eton with his father Prince Charles

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The young prince takes part in a photocall on his first day at Eton College

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In his bombshell memoir Spare, Harry alleged that William ‘told me to pretend I didn’t know him’ while both boys were at Eton

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The Wales brothers both attended Eton College (pictured). William started in 1995 while Harry started in 1998

Harry started at Eton in 1998 – three years after William started attending the prestigious private school.

But in his bombshell memoir Spare, he alleged that William ‘told me to pretend I didn’t know him’.

‘For the last two years, he explained, Eton had been his sanctuary. No kid brother tagging along, pestering him with questions, pushing up on his social circle.

‘He was forging his own life, and he wasn’t willing to give that up.’