The strict rule Kate Middleton must follow when it comes to her favourite hobby.

It’s a hard life being a royal. There are just so many fun things you’re not allowed to do. You can’t eat pasta or hold your beloved’s hand in public. Taking selfies is strictly prohibited – but that kind of makes sense seeing as you’re not allowed an Instagram account to post them on anyway.

Now it has emerged that the Duchess of Cambridge, Kate Middleton is forbidden from doing even more than we thought.

You see, despite sporty Kate’s love of running, you will never see her take part in a marathon.

Royal rebels and the rules they broke…

The revelation was made by the Duchess’ friend, journalist and author Bryony Gordon during an appearance on British TV show Loose Women.

Bryony met Kate at the London Marathon in 2017 when Heads Together, the mental health campaign overseen by Kate, Prince William and Prince Harry was the race’s chosen charity.

When Bryony, who also works with the charity, asked Kate if she was running that day, Kate replied: “Oh no, security and all that.”

Oh. That kind of makes sense. The Duchess of Cambridge running through the streets of London on a day where there are around 40,000 other runners as well as 750,000 spectators could be a little bit risky to say the least.

She did, however, take part in a 100m sprint with the princes as part of a pre-race engagement, proving it’s not her lack of fitness preventing her from taking part.

To be honest, being banned from running 42km might be one of the only royal rules we could get on board with.

Would you be fine with never running a marathon in your life? Tell us in the comments.