While members of the royal family now always pack a smart black outfit whenever they travel, such an important protocol wasn't always the case. The measure was only introduced when Queen Elizabeth found herself without the correct ensemble when news of her father King George VI's unexpected death reached her during a visit to Kenya in 1952.
HELLO!'s special issue, Queen Elizabeth II: A Centenary Tribute, published earlier this year, describes how the late monarch had travelled to Africa in place of her 56-year-old father, who had been in poor health for some time. King George VI was battling cancer and four months earlier had undergone an operation to remove part of his lung.
© Getty ImagesStill, it was a shock to the then-Princess, aged 25, to find out that she had said goodbye to him for the final time. She was staying at the rural Treetops Hotel near the town of Nyeri with her husband Prince Philip when her father died in his sleep in Sandringham.
However, news of the King's death only reached the couple - who were parents to Prince Charles, three, and two-year-old Princess Anne - when they had moved to Sayana Lodge, beside Mount Kenya. The Prince, then 30, was told of the King's death, and he passed the heartbreaking message on to his wife.
The Princess immediately prepared to return to the UK early; however, she realised that she had only packed light summer dresses for the trip and no black mourning outfit to wear. Indeed, it is customary for members of the royal family to wear only the dark shade from news of death until shortly after the funeral takes place - as was seen in the days after the Queen's death at Balmoral almost four years ago.
© Getty ImagesQueen Elizabeth II's quick change
As such, when the young Queen's plane landed back in London almost exactly 70 years before her own passing, a suitable ensemble was brought to her so that she could change on board before she disembarked. It is a misjudgement that forever reshaped royal protocol, and now all members of the family are certain to pack an appropriate outfit in their luggage just in case.
© SSPL via Getty ImagesThe Queen, who would officially accede to the throne at her Coronation in 1953, descended the aircraft steps at Heathrow Airport to be greeted by then-Prime Minister, Winston Churchill. She was dressed in a black coat with a matching black hat.
In 1992, the sartorial rule was honoured again when Princess Diana's father, Lord Spencer, died while she was away in the Alps skiing with then-husband Prince Charles. On their way back, the royal couple dressed in all-black attire.
Royal travel rules
This is far from the only travel rule the royal family must adhere to. The royal family is always pictured stepping off long flights looking impeccably styled and wrinkle-free. It turns out there's a simple trick: they don't wear their official outfits during the flight.
According to royal author Marcia Moody, they wear comfortable travel clothes for most of the trip, only changing into their formal attire moments before landing to avoid creasing or spilling on their clothes.
The most famous guideline prohibits immediate heirs from flying together on the same aircraft in order to protect the lineage of the throne in the event of a fatal crash. As flight safety has improved over the years, however, senior royals have increasingly ignored this rule.
For example, Prince William and Prince Kate regularly travel with Prince George and Princess Charlotte, while Prince Harry and Meghan Markle famously brought Archie on their 2018 tour of Southern Africa.
Perhaps the most unusual royal travel rule, however, concerns medical emergencies. When the monarch travels, particularly to regions where safe blood supplies might be limited, they are joined by a personal doctor who brings bags of blood that match the sovereign's exact type.
