Princess Kate and other members of the Royal Family reportedly follow an old superstition that warns them against eating pointy food, according to an expert.

This means that square-shaped sandwiches are off the menu, with former royal chef Graham Newbould explaining that this belief about food has been passed down for generations.

The Royal Family apparently are fearful that anyone who serves them pointy food is trying to do the monarchy harm, leading to some restrictions for their culinary team.

In the documentary Secrets of the Royal Kitchen, Nr Newbould revealed: “The royals never have square sandwiches because tradition has it that anyone presenting them with pointed-edged food is trying to overthrow the throne of England.”

The former royal chef spent two years working at Buckingham Palace and six years at Kensington Palace, but never once prepared square sandwiches for the late Queen Elizabeth.

The Royal Family always avoid pointy food (Image: Getty)

Instead the late monarch favoured “jam penny” sandwiches which she would tuck into with afternoon tea.

Queen Victoria’s husband Prince Albert also followed similar food superstitions, reportedly avoiding eating anything that was shaped like a coffin.

Royals have strict rules surrounding what they can eat when they travel, which were implemented by Queen Elizabeth when the Firm go on visits abroad.

Queen Elizabeth had strict rules about what the royals could eat (Image: Getty)

Top of the list of foods to be avoided is shellfish due to the high risk of food poisoning associated with it, as Grant Harrold told Woman & Home magazine: “It’s a very sensible move to abandon having seafood when out and about on public duties.

“We don’t want a member of the Royal Family having a serious reaction to food poisoning. Especially if she is on an overseas tour.”

The late Queen was also said to not be a fan of pasta or potatoes, and eating garlic was banned due to the possibility of bad breath.

King Charles implemented a ban on foie gras in 2008 due to welfare concerns over the treatment of ducks and geese being reared to provide the food.

King Charles banned foie gras from royal events (Image: Getty)

Former royal chef Darren McGrady offered an insight into the King’s breakfast habits, as he is particularly concerned with eating fresh local produce where possible.

He told Delish: “He normally starts the day with some fruit for breakfast, often some plums from the garden that have been lightly poached. A little juice and some muesli to go with it.”

Mr Newbould elaborated: “Wherever the Prince [King] goes in the world, the breakfast box goes with him.

“He has six different types of honey, some special mueslis, his dried fruit and anything that’s a bit special that he is a bit fussy about.”