Prince William broke a royal rule while on tour with Prince George

By Ainhoa Barcelona

One of the highlights of any royal tour is when the Cambridges first arrive in a country and the plane doors open, leaving Prince William, Kate, Prince George and Princess Charlotte to make their grand entrance. Some of the cutest family portraits are taken at this moment and excitement reaches fever pitch among fans and well-wishers. But according to royal protocol, these moments should not technically happen.

Prince William should never take the same flight as his heir – in this case four-year-old Prince George – to protect royal lineage. While there is no official rule in place, and heirs have travelled together in the past countless times before, the royals must seek permission fromthe Queen, who has the final say on the matter.

TAP FOR GALLERY Princes William and George should not travel on the same flight.

This would explain why William, 35, has been allowed to travel with his son on royal tours. He was granted permission from the Queen to bend the rules when his son was just nine months old; George accompanied his parents on a tour of Australia and New Zealand in 2014. Last September, the Cambridges also travelled as a family of four to Canada with Princess Charlotte. And in July of this year, the family toured Poland and Germany, boarding three flights together.

The royals have broken with tradition before on tour.

In general, the Cambridges tend to support their own country and fly British Airways when they can. They have occasionally flown by private jet on holidays but for royal tours, Prince William and Kate often take a commercial flight. The future King has even been pictured on a Ryanair flight before, and he and Kate again chose a budget airline to fly to their cousin Zara Tindall's wedding in Edinburgh in 2011.

The Duchess, whose mom and dad both worked for British Airways, is very accustomed to flying commercial. While the royals may not always fly private, they never fly without their top-notch security team of personal protection officers. They also have a large entourage, usually consisting of their private secretaries, press officers, nanny and Kate's stylist and hairdresser.

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