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Unlike their cousins, Meghan Markle and Prince Harry, the royal wedding of Princess Eugenie and Jack Brooksbank will be unlike any before it because of this one rule.

Commendably, the ninth in line for the throne has decided to enforce a strict ‘no plastic rule’ for the entire event – not an easy feat when you’re inviting 1,200 members of the public along with hundreds of guests.

Speaking to British Vogue’s fashion features editor, Ellie Pither, in this year’s September issue, the royal shared her environmental passions and said she keeps her Ivy Cottage home in Kensington Palace plastic-free.

“At the moment I’m picking up the mantle of anti-plastics, so I work with Project Zero which has just partnered with Sky Ocean Rescue,” said the 28-year-old.

“My whole house is anti-plastic now — and Jack and I want our wedding to be like that as well. We’ve got to look after this planet.”

I’m so excited to have recently become an Ambassador of Project 0 whose aim is to restore and protect the ocean. Today we launched our new partnership with @skyoceanrescue and of course, Plasticus, the whale made of used single use plastic…Together we aim to inspire people to make sustainable choices to stop the ocean from drowning in plastic. #passonplastic @weareprojectzero

A post shared by Princess Eugenie (@princesseugenie) on Jun 7, 2018 at 11:50am PDT

Princess Eugenie also spoke of her environmental concerns in June when she first became an ambassador for Project Zero – an organisation which aims to restore and protect the ocean.

“Together we aim to inspire people to make sustainable choices to stop the ocean from drowning in plastic,” she wrote in an Instagram caption promoting their work.

Although Meghan Markle and Prince Harry didn’t enforce a similar rule, instead of wedding presents, the couple asked their guests to donate to a list of selected charities, one of which included Surfers Against Sewage.

According to Global Citizen this move quadrupled donations to the charity which aims to end marine plastic pollution.

A post shared by Kensington Palace (@kensingtonroyal) on May 19, 2018 at 7:27am PDT

The royal wedding of Princess Eugenie and Brooksbank will take place on October 12 at St George’s Chapel at Windsor Castle, which was the same place Prince Harry and Meghan Markle got hitched in May this year.

Some famous celebrity faces we’ll most likely be seeing include the likes of singer and songwriter Ellie Goulding, George and Amal Clooney, the Beckhams and Cindy Crawford and her husband Rande Gerber who co-founded Casamigos – the tequila brand Brooksbank is an ambassador of.

Cara Delevingne, Kate Moss, Suki Waterhouse, Naomi Campbell, Sir Elton John and James Blunt could also be in attendance.

When attending a royal wedding, guests needs to abide by certain rules. Here are the do’s and don’t’s.