Kate Middleton apparently can’t wear this when flying

When it comes to royal fashion, there are many rules to follow, and it may surprise you to hear that includes travel too.

For example, Kate Middleton's dresses have their own seat on the plane for this reason, she often has to wear hats when she lands, and royals always travel with this one outfit for this slightly morbid eventuality.

And while it's tempting to think the Duchess of Cambridge might just like to travel in comfies like the rest of us, it seems like there's a protocol for that too.

According to etiquette expert Anne Chertoff, who spoke to Express.co.uk, royals have to dress up as a sign of 'respect' to the people they are visiting.

'When members of the Royal Family are on an official state trip on behalf of Queen Elizabeth II they are working, just as anyone else on a business trip. It’s appropriate for them to dress well to show respect to the people they are meeting with.'

So that's why you'll never see Kate stepping off a plane in jeans and trainers, with no makeup on and her hair in a bun.

That said, we'd like to think that behind closed doors, say on a long haul flight on a private jet, she would change into some sweats and comfie socks. You never know.