Camilla's longtime friend has revealed how King Charles surprised Prince George and other members of the Coronation party just moments before the flypast.
Lady Fiona Lansdowne, one of the Queen's Ladies in Attendance, appeared on Buckingham Palace's balcony alongside senior members of the Royal Family yesterday.
Charles and Camilla, in lavish robes and wearing their crowns, waved to the cheers of crowds who braved downpours during a ceremonial military celebration not seen for 70 years.
Prince William and Kate and their children, Prince George, Princess Charlotte and Prince Louis, joined the monarch and his wife before well-wishers were treated to an encore with just the King and Queen.
George, 9, was one of his grandfather's pages of honour and made history as he became the youngest future monarch to have a role in a coronation.
The sound of cheers swelled when the royals appeared on the balcony and shouts of "God save the King" could be heard.
There were even screams from the thousands of excited fans and the volume of cheers turned up a notch when Charles and Camilla waved.
Recalling the momentous occasion, Lady Lansdowne told the BBC: "We only knew we were going on the balcony one minute before. They didn't tell us or the pageboys.
"It was a little gift I think, but also I think they slightly realised that without the boys holding the trains, the Queen would've been dragged back because they don't slide very easily on a carpet.
"So the boys needed to be there, and then we were just told we were all getting on the balcony, and that was an extraordinary thing."
She added: "Never, ever did I think I would be on a balcony. I don't believe that I was there now really.
"You could feel the enthusiasm in the crowd, just all those wonderful people out in the rain - it was the most extraordinary experience.
"This grand swell of singing, chanting, shouting and clapping - it was absolutely extraordinary. And for those little boys, something they will never forget."
Despite the memorable balcony appearance, royal fans did not quite get the spectacular six-minute flypast they hoped for, after it was scaled down to two and a half minutes due to "unsuitable weather conditions".
More than 60 aircraft from the Royal Navy, British Army and Royal Air Force had been due to take part.
But the event only involved helicopters and the Red Arrows aerobatic display team - however, the crowd appeared no less thrilled.
The royal family spent a little under 10 minutes on the balcony before going back inside.
The King and Queen then re-emerged moments later to the delight of the crowds watching below.
Camilla then called for their pages to help them rearrange their trains, and they went back into the palace shortly before 2.40pm, with the King lingering for one final wave.
Michelle Roycroft, from London, was one of the first people to make it to the palace ahead of the big moment.
"I'm absolutely blown away. So excited," she said as she reached the railings.
Ms Roycroft had been waiting since 7am but was not bothered by the rain.
"It didn't matter at all," she said.
Speaking about her experience of watching the balcony appearance and the flypast, she said afterwards: "Absolutely made my day. The most memorable, magical day."
The Buckingham Palace balcony is one of the most famous in the world and one the royal family have stepped out onto many times before, often as part of a celebration.
Memorable appearances from the last few years include William and Kate's wedding in 2011 - when the crowd was treated to not one but two kisses - and the late Queen's Platinum Jubilee last June where Louis's comical reactions stole the show.
The first recorded royal balcony appearance took place in 1851, when Queen Victoria stepped onto it during celebrations for the opening of the Great Exhibition.
Since then, royal balcony appearances have marked many occasions from Queen Elizabeth II's annual official birthday celebrations to watch the RAF Flypast at the end of Trooping the Colour, royal weddings, jubilees, as well as special events of national significance such as the 75th anniversary of the Battle of Britain.
