For any older couple, the death of their grandchildren’s mother is a moment of grief, but also a time when the impact on the whole family can be devastating. When you have to deal with the situation with the whole world watching on, and commenting on your actions, it becomes even more challenging. Twenty years ago, the death of Diana plunged the royal family into chaos. It drew millions onto the streets, exposed the divisions within British society and unleashed an outpouring of public anger against the monarchy that threatened its stability. If in life Diana had been troublesome and difficult, in death she proved a force beyond control, which drove the Queen and Prince Philip to despair as they saw everything they had worked so hard for come close to being destroyed.

The royal family, holidaying in their Highland fastness at Balmoral that summer, had no inkling of the crisis about to overwhelm them when they received the news that Diana had been killed in a car crash in Paris. The call came through from the embassy in the French capital at 3.30 on the Sunday morning of 31 August 1997, and their first reaction was simply one of dazed bewilderment.

The Queen and Philip were stunned and shocked. Both in their seventies, they were aware of the problems Diana’s relationship with Dodi Fayed was causing, but they never expected it to spiral out of control in such a dramatic way. They had recognised the potential in their daughter-in-law in their different ways and saw her loss for the terrible waste it was. Now they were about to find out just how potent a symbol Diana had become.

Initially, the Queen had been woken by her page at 2am to be told that the princess had been involved in a fatal crash. The first information coming in from Paris was that Dodi Fayed was dead but that Diana had miraculously survived. Pulling on her old-fashioned dressing gown, she had immediately gone out into the corridor, where she met Charles coming out of his own bedroom three doors away on the first floor of the castle.

By then the whole castle had been stirred from its slumbers. Sir Robin Janvrin, the Queen’s deputy private secretary who was in attendance that weekend, had taken up his position in the equerries’ room on the ground floor and was liaising with the embassy in Paris. Footmen and staff had been roused and the Balmoral switchboard, through which all calls are made, was fully manned.

Prince Charles went into his sitting room, which is next to the Queen’s dressing room, to take the calls now coming in, some through the switchboard, others on his mobile telephone, which vibrates instead of ringing. The Queen ordered tea, which was brought up from the kitchen downstairs in a silver teapot and then ignored, as mother and son, joined by Prince Philip, paced up and down, anxiously asking each other what was to be done.