As Prince George celebrates his 12th birthday on 22 July, a time-honoured royal protocol quietly comes into effect — one that could have lasting implications for how he travels with his family.

While the young prince spent the day with his parents, Prince William and Princess Kate, and younger siblings Charlotte and Louis, this milestone marks more than just another candle on the cake. It also signals the point at which royal tradition begins to treat him not just as a child, but as a future monarch-in-waiting.

Why Prince George may no longer fly with Prince William

It’s a longstanding — though unofficial — royal custom that direct heirs to the throne do not travel together. The reason is rooted in preservation: to avoid the risk of multiple heirs being endangered in the same incident.

Historically, this rule came into play when Prince William turned 12 in 1994. From then on, he was no longer allowed to fly in the same aircraft as his father, King Charles (then Prince of Wales), or his brother Harry, unless granted special permission from the reigning monarch.

Graham Laurie, the former royal pilot, once recalled: “We flew all four: the Prince, the Princess, Prince William and Prince Harry, up until Prince William was 12 years old. After that, he had to have a separate aircraft.”